It is no use being fanatic about these things. There are people who simply cannot live if they don’t have meat. A person must consider carefully whether he really will be able to get on without it. If he does decide he can do without it and changes over from a meat to a vegetarian diet, he will feel stronger than he was before. That’s sometimes a difficulty, obviously: some people can’t bear the thought of living without meat. If, however, one does become a vegetarian, he feels stronger — because he is no longer obliged to deposit alien fat in his body; he makes his own fat, and this makes him feel stronger.
I know this from my own experience. I could not otherwise have endured the strenuous exertion of these last twenty-four years! I never could have traveled entire nights, for instance, and then given a lecture the next morning. For it is a fact, that if one is a vegetarian one carries out a certain activity within one that is spared the non-vegetarian, who has it done first by an animal. That’s the important difference.
But now don’t get the idea that I would ever agitate for vegetarianism! It must always be first established whether a person is able to become a vegetarian or not; it is an individual matter.
Source: Rudolf Steiner – GA 354 – The Evolution of the Earth and The Influence of the Stars – Lecture VI – Dornach, July 31, 1924