Beginning in 1400, English men and women gained increasing access to practical medical and scientific knowledge, first in vernacular manuscript collections, and later in inexpensive, printed books. More than two hundred years of engagement with this knowledge—much of it very old—in recipes, prognostications, almanacs, and other pragmatic texts, gradually encouraged readers to see themselves as adjudicators and even progenitors of knowledge in their own right. This talk explores how 15th century