"The popular idea is, of course, that meat is the only food which gives strength, and that Vegetarianism is wellnigh impossible. Don't you feel very weak ? " is generally the first question asked of a Vegetarian, by a new friend or acquaintance ; and if we press for a clearer explanation of this vague belief in the strengthgiving qualities of meat, we find that it is composed of two distinct and sometimes contradictory notions — first, that meat is necessary to support bodily strength ; secondly, that mental work cannot be done without it."
January 1, 1970
https://en.wikiquote.org/wiki/A_Plea_for_Vegetarianism_and_Other_Essays