Henry Daniel was a late fourteenth-century medical writer, horticulturalist, and Dominican friar. His Middle English medical treatise, the Liber Uricrisiarum (written and revised c. 1375-82), is the earliest known substantial medical treatise in post-Conquest English.

After completing the Liber Uricrisiarum, Daniel compiled an extensive herbal, sometimes known as Aaron Danielis. In the herbal, Daniel frequently refers to his uroscopy treatise, labelling it “(our) Uricrisis” and sometimes even citing book and chapter for particular self-citations.  The entry from the herbal on the plant rosemary circulated independently, with nearly twenty surviving copies.  A hitherto unnoticed text that should also be attributed in some way to Daniel is an incomplete treatise on astrological “nativities” in Wellcome MS 411, which includes two cross-references – one of them in the first person – to the “libro vricrosiarum” and the “boke of vricrosiarum.”

Despite attempts to locate Daniel in external documentary sources, the only definite information we currently have about his life must be gleaned from personal comments in his own works.  From these we learn that at some point Daniel had a garden with 252 plants in Stepney, in what is now East London (“Stebenhyþe bysyde London”); that he had traveled for seven years when he was young in order to learn about plants; that he was sometimes present at the treatment of patients, and sometimes provided herbs for medical use; that he was familiar with plants in locations ranging from Kent, Wiltshire, and Bristol to East Anglia and Lincolnshire; that he was relatively old and infirm when he came to write his two major works; and that he could not always find or afford the sources he wanted.  He mentions ‘maintaining himself’ at some point before taking up his written works (perhaps an indication that he joined the Dominicans in midlife), and he reports several case histories of patients that suggest he took an interest in collecting details of successful and unsuccessful medical treatments.  Some scholars (Hanna, Friedman, R. F. Green) have suggested that he was a member of the Dominican friary in Stamford, Lincolnshire, which is plausible enough given some of the geographical references within the text, but still awaits documentary support.

Daniel speaks of consulting with both physicians and apothecaries, some of whom he praises as worthy or wise, but he also recognizes that absolute expertise can be found in neither group and that even textual authorities can sometimes be mistaken.  He refers more than once to ignorant, greedy, and arrogant physicians (including some in his own religious order), unreliable apothecaries, and bungling “smatterers” in herbal science.  He reports various patients who devised their own successful treatment regimens, sometimes after professional physicians had failed to diagnose or cure them.  He mentions several noble and other women whose herbal remedies he has learned or contributed to, and at least one plant in his Stepney garden came from the herb garden (herber) of Queen Philippa (1314-1369), wife of King Edward III.

Daniel’s educational history is relatively obscure: he says in the Prologue to the Liber Uricrisiarum that no man taught him about medicine, but he clearly had access to a well-stocked library that included most works required in medieval medical curricula.  He is comfortable with philosophical texts and terms as well, including Aristotle’s Metaphysics and Sophistical Refutations, and such standard philosophical concepts as form, habit, and the categories of causation.  Although no university records have yet been found for him at Cambridge or Oxford, it seems likely that he had some university education, even if he learned medicine from books rather than teachers.