Abstract In the eighteenth century, Japanese honzōgaku developed to engage more actively with an empirical mode of study that put more emphasis on sensory and visual information, complementing the classical texts from China and Korea and correcting the names contained in these texts. The further introduction by honzō scholars of observation and accurate illustration, as well as of the use of material artefacts such as specimens, developed alongside the continued importance of the philological study of the classics, rather than replacing it. Using as primary materials the “Records of Medicinal Ingredients” found among the Documents of the Tsushima Clan, this essay examines a Japanese project to survey flora and fauna in Korea during the Edo period in order to shed light on the growing emphasis on visual accuracy in the study of nature. It also highlights how the circulation of texts inspired changes in how people conceived of natural objects and constructed materia medica knowledge in the context of Tokugawa Japan.