Henry Daniel is perhaps the most neglected English writer of the 14th century. An older contemporary of Chaucer, he worked in London and the Midlands on a giant project to make Latin medical and scientific writings accessible to an English audience. We have hundreds of pages of his two great texts: a uroscopy, to provide the foundations of medical practice, and a herbal, to provide the remedies for the ailments diagnosed by means of the urine flask. In his works he created an original vocabulary, developed an elaborate scholarly system of cross-references and proto-footnotes, deployed a variety of didactic devices from rhymes and diagrams to mnemonics and the volvelle, and incorporated his own experiences as a gardener and physician into the learned texts he translated. Daniel has been barely noticed by modern medical historians, lexicographers, and scholars, and acknowledgement of his scientific and literary achievement is long overdue.