Jan Dirk Blom, author of A Dictionary of Hallucinations, is a clinical psychiatrist and assistant professor of psychiatry in the Netherlands who holds a doctorate in philosophy. The Dictionary incorporates both of his domains of study as he explores his topic in this focused work of historical inquiry that “aims to reappraise the concepts of hallucinations, illusions, and sensory distortions developed during the era of classic psychiatry and advocates to incorporate them into our current scientific discourse” (p. vi). However, the relatively large scope of the book and an obvious, if not entirely misplaced, allegiance to the liberal arts, while making it fascinating, obscure Blom's goal. The book consists of alphabetical entries divided into fairly distinct categories: definitions of hallucinatory symptoms, medical conditions and substances associated with the mediation of hallucinations, definitions of the terms “hallucination” and “illusion” by important historical authors, historical figures who are known to have experienced hallucinations, and miscellaneous issues. Each definition includes a meaning, and where possible, etymological origin and date of introduction, reference to the authors who introduced the term, etiology and pathophysiology of the symptom, related terms, and relevant bibliographic references. Moreover, cross-references abound, allowing for multiple access points for the reader. Blom attempts to create a much-needed baseline of definitional standardization in an effort to control the terminology relating to hallucinations, which is a necessity if Blom wishes to be successful in his reconciliation of classical psychiatry with contemporary clinical and research science. Lexical shifts can too easily mark a break in the history of a contemporary concept. While A Dictionary of Hallucinations is recommended for large academic libraries, especially those with a medical history collection, it is problematic for clinical or research-oriented organizations. Much of the book's fascinating elements serve to make it cumbersome for the practitioner. It is curious that, given Blom's desire to be relevant to scientists, two of categories that he included are definitions of the terms “hallucination” and “illusion” by historical figures and biographies of those known (or believed) to have had hallucinations, neither of which category is particularly germane to contemporary scientific inquiry. Additionally, the book contains “other misperceptions,” such as multiple entries on the various kinds of color blindness. These inclusions, while not uninteresting in the abstract, stand in the way of quick consultation. The most useful entries are likely those that include etiology and pathophysiology of a symptom. For instance, knowing that “bagel vision” is indicative of migraine is more clinically valuable than knowing that William Blake may have suffered from bipolar disorder or temporal lobe epilepsy. Again, while interesting, this added information complicates clinical use. There are other inclusions that, while not detrimental to the goals of the book, do not really benefit the intended audiences: researchers, clinicians, and historians, alike. For instance, the book has over 100 illustrations, images taken mostly from the public domain (except for a few photos from the 1960s and some author-created images), but the illustrations do not substantially increase the overall value of the work. The inclusion of engravings from the nineteenth century adds to the historic flavor of the entries—after all, many are drawn from that rich period of psycho-neurological inquiry—but the handful of entries named for Bohemian physiologist Johannes Evangelista Purkyně (Purkinje afterimage, Purkinje effect, Purkinje figure, etc.) are not significantly enriched by a drawing of Purkyně done in the early 1800s. Additionally, each of the many entries describing a psychoactive substance ends with the statement, “A person intentionally employing [substance] for the purpose of exploring the psyche may be called a psychonaut.” While this may be a fact, it is a fact inessential to the definition, and the decision to include it so often hints at an unrevealed authorial agenda. A Dictionary of Hallucinations is highly researched, thoughtfully and logically constructed, and, except for some minor quibbles, makes sense as a whole. Even the entries on color blindness, while not clinically useful, belong in an academic discussion of misperception that places color blindness in the same general area as hallucination. The citations at the end of each entry can be very useful for the researcher looking for a starting point. But the book is a hybrid of historical research and clinically useful information, and that might make it a difficult fit in some collections where money and space must be spent on only the most clinically expedient volumes.