There are no astrolabes decorating Geoffrey Chaucer's tomb. As we might expect, its Latin epitaph remembered Chaucer as a poet, and not as a stargazer nor as a technical writer. In life Chaucer was all of these.1 In the 1390s, as he finished the bulk of his Canterbury Tales, he found time to stargaze and to compile a Middle English Treatise on the Astrolabe translated from Latin and French sources, themselves translations of Arabic texts on the astrolabe.2 Its topic can feel esoteric and obsolete these days: how many of us, after all, have relied upon on an astrolabe to tell time by the night sky, or track the sun's progress through the houses of the zodiac, or measure the height of some terrestrial thing? Centuries of readers, quite understandably, have gravitated to the richness of storytelling and social life on display in the Canterbury Tales. And while the Astrolabe has attracted more critical interest from scholars recently, it still occupies a peripheral place in the Chaucerian canon, a dimmer satellite in the universe of Chaucer's literary making.3 His legacy as a poet easily eclipses his more modest one as an early writer of vernacular science.In his prologue to the Treatise on the Astrolabe, however, Chaucer proffers an ordinary astrolabe, and this pragmatic Middle English guidebook for its use, as part of the worldly legacy he leaves to his young son: Lyte Lowys my sone, I aperceyve wel by certeyne evydences thyn abilite to lerne sciences touching nombres and proporciouns. And as wel considre I thy besy praier in special to lerne the tretys of the astrolabie. Than for as moche as a philosofre saith: he wrappith him in his frende that condescendith to the rightfulle praiers of his frende, therfore have I yoven the a suffisant astrolabie as for oure orizonte compowned after the latitude of Oxenforde.4Usually when Chaucer writes himself into his poetry like this, his self-portraits are comically self-deprecating. The portly pilgrim Geoffrey is an awkward companion on the road to Canterbury, always looking at the ground, whose own Tale of Sir Thopas flops before he resorts to prose. The narrators of his dream visions are bookish loners and hapless lovers. His authorial personae stumble around in worlds of his own design. Here in the prose prologue to the Astrolabe, however, readers find Chaucer as if speaking in his own voice, plain and simple, as he translates medieval science into plain English. Whereas Chaucer so often shrouds his poetry behind the scrim of a dream or masks his own voice by speaking through Canterbury pilgrims and dreamer-narrators, the prologue to the Astrolabe stages an intimate domestic scene in which the poet seems to play himself, a doting father and astronomical enthusiast with nothing up his sleeve.Yet just as Chaucer would seem to reveal a little of himself, he deflects our attention with two gestures towards two other elusive figures. First, there is the address to his son “lyte Lowis” Chaucer. Outside of this prologue, Lewis is hard to track down. The documentary record remembers Lewis Chaucer only for collecting wages as a soldier in 1403, some ten years after Chaucer dedicates the Astrolabe to him.5 So scantly recollected, Lewis now appears as only a minor character in his father's biography, as a precocious student of astronomy and a figure for the audience of the Astrolabe. Little Lewis Chaucer keeps company in the prologue with another figure who has long managed to slip the grasp of modern explanation: this anonymous “philosofre,” conjured to supply some proverbial authority on the duties of a good friend. Readers of the Astrolabe are invited to identify with the eagerness of ten-year-old Lewis, while its writer speaks with the easy, axiomatic authority of someone who quotes philosophers in casual conversation—even if he can't be bothered to name his sources properly.These elusive figures warrant tracking down because this framing device looms over the ensuing argument for Middle English translation mounted in the prologue to the Astrolabe. Chaucer articulates a theory of writing in the vernacular in this adopted voice of the doting father in the prologue: This tretis . . . wol I shewe the under full light reules and naked wordes in Englisshe: for Latyn canst thou yit but small, my litel sone. But natheles suffise to the these trewe conclusions in Englisshe, as wel as sufficith to these noble Grekes these same conclusions in Greke. And to Arabiens in Arabike. And to Jewes in Ebrewe and to the Latyn folk in Latyn, whiche Latyn folke had hem first of othere dyverse langages, and wroten hem in her oune tunge. (ll. 20–29)Thus Chaucer reassures his son of the sufficiency of English to communicate the old techniques of practical astronomy (its “conclusions”) in a new way, expressed in a light and accessible style natural to it. The prologue expresses a confidence in the capabilities of one's own tongue, couched here in this scene of private bequest. This scene resonated with early readers of Chaucer, who would credit the poet with uplifting his own tongue, English, into new prestige.6 And indeed, in the fifteenth century, his prose treatise of elementary astronomical instruction found nearly as broad an audience as his poetry. To cite one measure of its popularity, the Treatise on the Astrolabe survives in thirty-three manuscripts, second only to the Canterbury Tales among Chaucer's works.7While little Lewis has been lavished with critical attention, few have chased after Chaucer's fugitive “philosofre” with the same interest.8 I have found him hiding out among those “Latyn folk” of the prologue: the “philosofre” was one of many Latin writers who translated medical texts from Greek, Arabic, and Hebrew in the eleventh century and afterwards. This philosopher calls himself “ego, Platearius” in a medical text called the Practica brevis, where he offers this maxim on friendship in his own prefatory scene of dedication.9 Discovering the proverb's Latin source reveals a tension at play between the prologue's twin gestures: a superficially modest one toward a ten-year-old son and another more obscure one to this unnamed medical writer. With one hand, Chaucer beckons welcomingly to little Lewis with his “small Latin” and readers like him, playing the humble translator and “lewd compilator” of this treatise.10 With another, he slyly points to the more remote learned tradition of academic medicine, of philosophers who introduced their own translations in congruent terms of affection and sufficiency. The prologue declaims its vernacular novelty and its Englishness; yet it does so in the fluent academic register of Latin folk, who wrote this way when they drew knowledge from diverse languages into their own tongue centuries ago. In this essay, I will describe that introductory register of Latinate medical translators to inform a new perspective on this framing scene of the Treatise on the Astrolabe. Latinate eavesdroppers listening in on this scene will recognize, in that address to his son, the signatures of an academic style beyond little Lewis's “small Latin.” This scene of homespun vernacular theorizing, I will show, follows a script cribbed from Chaucer's reading among the prologues of old philosophers like Platearius. I then reconsider the immediate afterlife of Chaucer's address to little Lewis, to revisit how other early readers of the Astrolabe imagined themselves as fellow ingenues, subjecting themselves to the authority of Chaucer's vernacular science, even if their Latin was not quite so small.When Simon Bredon drew up his will in 1368, he made particular provision for the fate of his books.11 Bredon's will is a testament to the life of reading lived by this scholar, physician, and astronomer of fourteenth-century England. He left an impressive personal library of academic medicine and astronomy behind to be parceled out to friends and a number of English institutions. More than to anyone or anywhere else, Bredon's will leaves his books to Merton College, Oxford: I leave my better Avicenna, and the books of Rasis and books of Galen in two volumes . . . the Passionarium of Galen, a book of surgery of Theodoric and Lanfrank and Henry of Mondeville in one volume; Ptolemy's Quadripartitum on judgments of astronomy, the book of Haly Abenragel On the Judgments of Astronomy, the book of Geber with those in one volume and another book, which I call the Minuta introductoria astronomia: all of these books I leave to the library of Merton College.12With passages like these, Bredon's will can read more like a library catalogue than as a legal instrument. His bibliographical method is variously specific, generic, and personalized. He calls one of his two copies of the Canon of Medicine his “better Avicenna,” distinguished from the other by some apparent difference in quality.13 He mistakenly esteems a text called Passionarum as the work of Galen (its true author, Gariopontus, had little of Galen's caché.) He invents his own name for a book he calls Minuta introductoria astronomia (“Little Introduction to Astronomy”). Bredon's mixed style of reference—according to conventional attribution, personal habits, or material form—encodes his personal understanding of textual distinction or value into this catalogue post mortem; in this shorthand, Bredon describes texts in ways that were meaningful to him and his fellow readers of natural philosophy at Oxford. There at medieval Merton, he joined a generational cohort of natural philosophers collectively known as the Merton calculators. His will bears witness to one attempt at ordering texts and books among this specialist community of readers.Bredon identifies one particular book by its opening words, along with its author and title: his “Practica of Platearius, which begins Amicum induit.”14 The Practica brevis, a twelfth-century medical manual, begins with a particularly recognizable aphorism: “Amicum induit qui iustis amicorum precibus condescendit” (He fashions himself a friend who accedes to the righteous requests of his friends). Its author, Platearius, was obliged to write his Latin medical guide because, he says, a dear friend asked him to. Beyond Bredon's will, the “Amicum induit” incipit crops up elsewhere in late-medieval England as it was borrowed as a proverbial point of departure from which to begin a text. One scribe making a fifteenth-century copy of John Arderne's Liber medicinarum (“Book of Medicines”) appropriates this maxim for a short prologue addressed to a friend.15 But the incipit circulated most widely among Middle English readers as it was cited for Lewis in the prologue of Chaucer's Astrolabe, without any explicit attribution to Platearius or to his Practica. Thus unmoored, this anonymous citation has flummoxed modern readers. Yet Simon Bredon's will expects a learned readership at medieval Oxford to recognize this saying of “a philosofre” readily. Indeed, his will invests it with a special purchase: the incipit of the Practica was as remarkable as its title and author.Bredon and his fellows at Merton were keen astrolabists. In the same will, he donates his “greater” astrolabe to Merton's library; he gives another to William Reed, who donates his astronomical instruments to Merton in 1382.16 No medieval institution could have too many astrolabes. Properly configured, the astrolabe's moveable components provided its users with an image of the half-dome celestial sky, flattened into two dimensions, for a specific latitude on the earth's surface for that specific time. Turned over and held to the eye, its back half could also be used as a sighting device with which one could measure the altitude of the sun or stars. With an astrolabe, one could measure the passage of time, calculate the height of terrestrial things, or track the sun's movement through the houses of the zodiac. Bredon's astrolabe would have come in quite handy for the readers of his many medical books left to Merton. This was because medieval medicine is everywhere engaged with the medieval sciences of the stars as necessary knowledge for prognostication and treatment. It follows, then, that readers of medical texts at fourteenth-century Oxford would cultivate a practical familiarity with the technology of those star-sciences.17 With his talent for numbers and proportions and his enthusiasm for astrolabes, it is easy to imagine Lewis Chaucer eventually fitting in among the Merton calculators (indeed some modern scholars, and one medieval scribe of the Astrolabe, have done just that).18Simon Bredon's will and Chaucer's prologue both witness to the same conjunction of this proverb of Platearius and the gift of an astrolabe. But these texts address themselves to drastically different audiences. The Treatise on the Astrolabe does not announce itself as the sort of text bound for study in the library of Merton College. Quite the opposite: Chaucer introduces the Treatise with that familial vernacularizing scene of a father writing for his ten-year-old son with only the barest knowledge of Latin. With its blend of silent scholarly citation and parental intimacy, the prologue to the Astrolabe presents a critical predicament: what sort of audience does Chaucer really expect for—or imagine for—the Treatise? One might imagine a learned readership, personified by Bredon, and comprised of Latinate, university-trained users of astrolabes who were familiar with the incipits of “philosofres.” But Chaucer addresses his prologue to his ten-year-old son with none of their Latinity. His son might figure for a wider swath of English readers, young and old, who are more comfortable in the vernacular, practically oriented, and inclined to astronomical inquiry, if unfamiliar with its technical terms of art. Yet what might strike us as a predicament in need of resolving might just as well be appreciated as a feature of its design. Vernacular texts could appeal equally to a vernacular audience without access to or knowledge of Latinate textual culture as well as to an audience steeped in that culture, by making that appeal in proper, conventional language. These prologues, that is, could accommodate modest self-styling and high academic style simultaneously. Authors’ overt claims to simplicity and clarity coexist with subtle markers of sophistication, in ways only clear to learned audiences who were primed to recognize them.Latin scientific prologues modeled a vernacular mode of apology for any Middle English translator who would presume to adapt scientific texts to a new language. These Latin prologues are themselves replete with scenes of familiar address to children, brothers, friends, and patrons who clamor for translations like little Lewis; these same prologues also assert the sufficiency of Latin as a language fit to communicate medical knowledge, just as Arabic and Greek long had done. Chaucer practices in this mode, and he adapts these conventions of the learned, Latin medical prologue to serve his own vernacularizing purposes in the prologue to the Astrolabe. To describe these introductory conventions, I will spend some time considering the prologue of Platearius's Practica brevis alongside the prologues of Constantine the African, the prolific translator of academic medicine out of Arabic into Latin. Chaucer's rhetoric of vernacular simplicity proclaims a naivety about—or perhaps a clumsiness with—the complexities of Latinate style. Don't be too persuaded by all that sandbagging. While Chaucer quotes a preface of Platearius directly, he deftly introduces his translation according to a generic template best exemplified by the Latin medical prologues of Constantine the African.We know very little about the “philosofre” Platearius, beyond his name.19 The Practica brevis ascribed to him appeared during a flourishing of Latin medical writing and translation in tenth- and eleventh-century Italy, in the orbit of Salerno.20 The prologue to the Practica brevis begins with a scene of petition, and a statement of compositional principles: Amicum induit qui [iustis] amicorum precibus condescendit. Justa igitur amicorum petitio effectui est celeriter mancipanda ne frigessere videatur karitas ociosa. Unde ego Platearius, dilectissimi, vestris precibus condescendens breviter causas, signa et curas egritudinum scribere proposui, ut vestrum laborem optatus consequator effectus et mihi vestra discretio gloriam pariat et honorem[. N]ec cuiuslibet egritudinis causas et signa et curas ad unguem prosequi me propono, tum quia verborum multiplicitas quorundam primitias perturbaret, tum quia in aliis aliorum operibus hec satis sufficienter sunt ostensa. Opus igitur propositum vobis socii morem gerens letus agredior nec de quacumque egritudine quelibet dicere sufficienter dicturus, sed tamen ea que experimento meliora didici et quibus uti consuevi frequentius et in quibus in manu mea optatum Deus prebuit effectum.21(He fashions himself a friend who accedes to the righteous requests of his friends. A righteous request from friends should be fulfilled quickly then, lest one's love might seem to have grown cool. Therefore, my dearest friends, I Platearius, acceding to your requests, have set out to write down briefly the causes, symptoms, and cures of diseases, so that your work might achieve its desired results, and thus your good judgment will redound to my own glory and honor. I do not propose to describe fully the causes, symptoms, and cures of every disease in fine detail, because the profusion of words would spoil its particular profit, and because these matters are treated sufficiently in other works, by other authors. I undertake this proposed work, therefore, in a happy mood, for you my friends, and in doing so I will speak sufficiently of things which need be discussed: not of any and all diseases, but rather of those better cures which I learned through experience and those which I am accustomed to using frequently, and which in my hands God has proven effective.)In this preface, Platearius espouses brevity: a “profusion of words” (multiplicitas verborum) would obscure its useful advice. He disavows comprehensiveness: his Practica will not cover “every disease” (cuiuslibet egritudinis) nor will it describe them in fine detail (ad unguem). His text will be shaped by his own experience (experimento): the Practica will include treatments the “philosofre” has himself found effective and jettison any advice which has failed in practice. The indispensable virtue of medical writing here is sufficiency: the Practica will be sufficiently comprehensive in its substance, and will strive to meet a standard of sufficient openness to which he holds other medical authors (sufficienter dicturus . . . sufficienter sunt ostensa). All this is offered as an affectionate answer to the requests of dearest friends: how else to prove himself a true friend, in the spirit of his opening maxim?Chaucer espouses analogous principles of style and selectiveness in his own prologue to the Astrolabe. Chaucer disavows comprehensiveness, too, proposing to teach only “a certein nombre of conclusions”: as he explains, he will include only those astrolabe techniques he finds practicable in his own experience (ll. 11–13). He apologizes for his “superfluite of wordes” in Middle English (l. 44). His self-deprecation here, and defensiveness about prolixity, assumes brevity to be cherished stylistic virtue. He also adopts the terms of sufficiency as the standard of communication to which his vernacular might live up: “suffise to the these trewe conclusions in Englissh”; “in all these languages, and in many moo, han these conclusions ben suffisantly lerned and taught” (ll. 30–31). All these echoes might be taken as further citations of the “philosofre” whose dictum introduces the Astrolabe. More conservatively, we can appreciate a shared rhetorical tradition at work here behind these prologues by the “philosofre” and the poet who quotes him. Both oblige their authors to intimate associates, both cite proverbial authority, and both argue for their own practices of compilation or style in similar terms of brevity and sufficiency.These rhetorical resemblances between the Practica and Astrolabe prologues evoke a broader mode of introduction common across the texts of the medical curriculum as Chaucer knew it. He outlines this medical curriculum in the General Prologue to the Canterbury Tales. There, the Physician is portrayed as an unscrupulous practitioner of medicine, profiting off of his patients’ misfortunes. But he impresses Geoffrey as an admirably scrupulous reader of medicine's revered authors: Wel knew he the olde Esculapius,And Deyscorides, and eek Rufus,Olde Ypocras, Haly, and Galyen,Serapion, Razis, and Avycen,Averrois, Damascien, and Constantyn,Bernard, and Gatesden, and Gilbertyn. (I.429–34)The General Prologue abbreviates the medieval medical syllabus as a series of names. It is something of a jumble, but it emplots medical history by implication, or at least, medical history as Chaucer would have known it. The series follows academic medicine from its purported mythical beginnings with Apollo's son “old Aesculapius,” through famed Greek writers, then Arabic ones, and finally into the Latin of the medieval West. Geoffrey's coursing summary of the Physician's reading alights finally onto English writers of Latin medicine like John Gaddesden and Gilbert the Englishman. This is translatio studii versified in miniature; so the Physician's reading list briskly demonstrates how serial acts of translations brought medical knowledge to Latinate Europe.Most renowned among Latinate medical translators was Constantine the African, or “Constantyn,” whom Chaucer positions at the joining of the Arabic canon with the medieval Latin one: between Avicenna and Averroes on one side, and Bernard of Gordon, Gattesden, and Gilbert on the other. A convert to Christianity from modern Tunisia, Constantine translated a number of Arabic medical texts into Latin as a Benedictine monk at Monte Cassino in the eleventh century.22 Many of these source texts were themselves Arabic translations of Greek works, like the Aphorisms of Hippocrates, complete with Galen's commentary upon it.23 Chaucer was undoubtedly a reader of Constantine's work. The desperate old husband January in the Merchant's Tale tries to make homemade aphrodisiacs following instructions which “the cursed monk, daun Constantyn, / Hath writen in his book De Coitu” (IV.1810–11). The elaborate recipes of the De Coitu give enough cause to curse this monk's name: one calls for the brains of thirty male sparrows, steeped in a glass pot, to be combined with the kidney grease of a billy goat.24 Constantine's convoluted recipes might have frustrated readers of his De Coitu, but his writings and translations elsewhere stimulated Chaucer's rhetorical senses. Take, for instance, how the first aphorism of Hippocrates inspired Chaucer to begin the Parliament of Fowls with this elegant rendering of it: The lyf so short, the craft so longe to lerne,Th'assay so hard, so sharp the conquerynge. (Parliament of Fowls, 1–2)The opening gambit of the Parliament of Fowls adapts this maxim on the hardships of medical practice to lament, instead, the trials and mishaps of love.25 Like his Physician in his Canterbury Tales, Chaucer himself had to have read “olde Ypocras” in Latin translation, and he almost certainly did so in Constantine's very popular translation of Galen's commentary upon them. Constantine introduces the first and most famous Hippocratic maxim—“vita brevis ars vero longa”—with a dedicatory preface, one that stages a scene of the translator's acquiescence to eager requests for this translation.26 Whereas Chaucer borrowed the first Hippocratic aphorism to make a start to his Parliament of Fowls, Constantine's preface to the Aphorisms might well have furnished Chaucer with another conventional template for beginning the Treatise on the Astrolabe. His prologue introduces the Latin Aphorisms so: Licet petitionibus tuis continuis acquiescens fili mi sepius diceres michi ut ex opusculis Galieni [aliqua] latine lingue transducerem ex lingua arabica diu tamen quia multum est negaui hesitans tanti philosophi transferre opera. Sed cum petere non desisteres et lingua latina tanto te carere viro pre dolore affici diceres, tandem condescendi tibi et opus quoddam supra amphorismos Ypocratis gloriosissimi transferre destinaui. Quod si perspicaciter quiuis intenderit, operam suam non amisisse congaudebit. Est autem in hoc opere materia prelucida uerba quoque ponderosa, quibus iunctis etsi Galienus poeta non fuerit, illud tamen satiriaci visus est [sibi] imitari, nam aut prodesse volunt aut delectare poete. In materie enim prosunt, in verbis ponderosis et prosunt et delecauit.27(Although I was sympathetic to your continual requests, my son, as you were very often urging me to translate the shorter works of Galen into the Latin language from the Arabic language, yet nonetheless for a long time I refused, because it was a great [tedious] thing, being hesitant to translate the works of such a philosopher. But since you would not stop making these requests, and since you said you were so undone by such grief that the Latin language should lack such a great man, I finally gave in to you, and set out to translate a certain work concerning the Aphorisms of the most glorious Hippocrates. Whoever understands this work clearly will rejoice to have not wasted the effort. There is, indeed, in this work brilliant material, and words of great weight, which in joining together, even if he was not a poet, Galen nonetheless thought himself to be imitating that famous line of the satirist, for “poets want either to be of service or to delight.” Indeed, in substance, they are a benefit, and in weighty words he delights.)Constantine here addresses Glaucus, his disciple and fellow monk, as “my son” (fili mi).28 He claims to translate the Galen's commentary on the Aphorisms to answer this son's “continual petitions” (petitionibus . . . continuis) for a Latin translation. He acknowledges a reluctance to undertake this translation out of humility before a weighty tradition, even as the preface records the moment of his eventual concession to these requests for Galenic work in Latin. Latin readers of the Galen's commentary, he says, will enjoy a double reward: its medical wisdom will prove useful, and its language delightful.Echoes between Constantine's prologue to Aphorisms and Chaucer's to the Astrolabe abound. The most notable of the similarities—and most central to the logic of Chaucer's justification of translating into his own vernacular—is found in the figure of the petitioning son, for whom both prologues claim their translations have been prepared. Constantine responds to the “continual petitions” of a junior monk he calls a son; Chaucer's Astrolabe prologue claims to answer the “besy praier” of a ten-year-old little Lewis. Constantine's other prefaces also make use of this device of filial address and petition, with sons figuring as first readers: his “dear son” Johannes receives On Fevers (De Febribus), by Isaac Judeus, as a reward for his tearful pleas.29 The preface to Galen's Megategni again addresses a “most beloved son” named Johannes, who he credits with a “piercing intellect in letters” (“charissime fili iohannes, acutissime ingenium habeas in litteris”).30 Constantine casts his motivations as explicitly paternal, as he says that he translates “on account of sincere paternal affection for you, dearest son” in the Megategni, and he is “moved by a father's love” to translate De Febribus from Arabic.31“Paternal love,” says Constantine, spurs him to translate Galenic medicine out of Arabic and into Latin for these beloved fellow monks at Monte Cassino he adopts as sons. Latin, after all, was something akin to a household vernacular among Constantine and his notional first readers—a shared, spoken language of the monastic house in which these intimate moments of dedication were transacted, and through which old texts were made newly legible. Latin is no abstract and impenetrable grammatica in these prologues, but a vital common ground. Constantine's translations flag the novelty of Latinate medical texts, while also pointing backwards at their routes through other languages. His prologue to the Aphorisms recounts the movement of this text across language and time: from Galen's Greek original, then into Arabic, and now into Latin (lingue latine . . . ex lingua arabica).32 In a preface to his translation of the De urinarum by Isaac Judeus, Constantine claims that he noticed an absence himself in the Latin medical canon: In Latinis quidem libris nullum auctorem invenire potui qui de urinis certam et autenticam cognitionem dederit. Unde ad linguam Arabicam me diverti in qua quendam librum in huiusmodi noticia admirandum repperi. Quem ego, Constantinus Africanus, Montis Cassianensis monachus, Latinae linguae ad transferendum destinavi dare, ut de labore premium animae adispicerer [& introducendis ad cognoscendam urinam ampliarem iter].33(I could not find any book written in Latin that gave certain and reliable information about urine. Hence I turned to the Arabic language, in which I discovered an admirable book of this kind. I, Constantine the African, monk of Monte Cassino, decided to translate it into Latin, in order to earn a reward for my soul with this effort, and that I should widen the path to knowledge about urine by introducing these things.)According to Constantine, his translation affords Latinate readers a newly navigable route to medical expertise. Latin is one more “path to knowledge” for those who may not “turn to the Arabic language” for further reading quite so easily as he does. This knowledge of uroscopy—diagnosis by inspection of urine—would have been indispensable to medieval readers. Constantine's prologue in