When Franklin (1706-1790) was about 16 years old he read a book by Thomas Tryon (1634-1703) extolling the health benefits of a vegetable diet. Although Franklin did not adhere to such a diet for prolonged periods of time, he periodically would become a vegetarian because it "promoted clearness of ideas and quickness of thought."
"At the time Franklin wrote the passage below he was serving as a printer's apprentice to his older brother, James.
When about 15 years of age I happened to meet with a book written by one Tryon,1 recommending a vegetable diet, I determined to go into it. My brother, being yet unmarried, did not keep house, but boarded himself and his apprentices in another family. My refusing to eat flesh occasioned an inconveniency, and I was frequently chid for my singularity, I made myself acquainted with Tryon's manner of preparing some of his dishes, such as boiling potatoes or rice, making hasty pudding, and few others, and then proposed to my brother, that if he would give me, weekly, half the money he paid for my board, I would board myself. This was an additional fund for buying books, but I had another advantage in it. My brother and the rest going from the printinghouse to their meals, I remained there alone, and, despatching presently my light repast, which often was no more than a brisket of a slice of bread, a handful of raisins or a tart from the pastry-cook's, and a glass of water, had the rest of the time till their return for study, in which I made the greater progress, from that greater clearness of head and quicker apprehension which usually attend temperence in eating and drinking."2