The Life and Opinions of Tristram Shandy, Gentleman

The whole secret of health, said my father, beginning the sentence again, depending evidently upon the due contention betwixt the radical heat and radical moisture within us; -- the least imaginable skill had been sufficient to have maintained it, had not the schoolmen confounded the talk, merely (as Van Helmont, the famous chymist, has proved) by all along mistaking the radical moisture for the tallow and fat of animal bodies.

Now the radical moisture is not the tallow or fat of animals, but an oily and balsamous substance; for the fat and tallow, as also the phlegm or watery parts, are cold; whereas the oily and balsamous parts are of a lively heat and spirit, which accounts for the observation of Aristotle, "Quod omne animal post coitum est triste."