Religio medici.

The most famous work of English literature written by a physician. Browne did not intend to have it published, but manuscripts of the work circulated privately. Two unauthorized and inaccurate editions were issued surreptitiously by the same publisher in the same year.

This was Sir William Osler's favorite book. He may have learned the entire work by heart, and was fond of giving copies of later editions to friends. Full text of the first and second editions from penelope.uchicago.edu at this link.