The book of Nature is that which the physician must read; and to do so he must walk over the leaves.
Source: From the Encyclopµdia Britannica, ninth edition, vol. xviii. p. 234.
-- Philipus Aureolus Paracelsus, (Nov 11 1493-1541), German-Swiss physician; He established the role of chemistry in medicine; published Die grosse Wundartzney (Great Surgery...).