about the domination of our intellect by our digestive organs

"How good one feels when one is full - how satisfied with ourselves and with the world! People who have tried it, tell me that a clear conscience makes you very happy and contented; but a full stomach does the business quite as well, and is cheaper, and more easily obtained. One feels so forgiving and generous after a substantial and well-digested meal - so noble-minded, so kindly-hearted.
It is very strange, this domination of our intellect by our digestive organs. We cannot work, we cannot think, unless our stomach wills so. It dictates to us our emotions, our passions. After egg and bacon, it says 'Work!'. After beefsteak and porter it says 'Sleep!'. After a cup of tea (two spoonfuls for each cup, and don't let it stand more than three minutes), it says to the brain, 'Now, rise, and show your strength. Be eloquent, and deep, and tender; see, with a clear eye, into Nature and into life; spread your white wings of quivering thought, and soar, a god-like spirit, over the whirling world beneath you, up through long lanes of flaming stars to the gates of eternity!'
After hot muffins, it says, 'Be dull and soulless, like a beast of the field - a brainless animal with listless eye, unlit by any ray of fancy, or of hope, or fear, or love, or life.' And after brandy, taken in sufficient quantity, it says, 'Now, come, fool, folly, and splutter in sensless sounds, and show what a helpless ninny is the poor man whose wit and will are drowned, like kittens, side by side, in half an inch of alcohol'.
Before our supper, Harris and George and I were quarrelsome and snappy and ill-tempered; after our supper, we sat and beamed on one another, and we beamed upon the dog, too. We loved each other, we loved everybody. Harris, in moving about, trod on George's corn. Had this happened before supper, George would have expressed wishes and desires concerning Harris' fate in this world and the next that would have made a thoughtful man shudder.
As it was, he said, 'Steady, old man; 'ware wheat.'
And Harris, instead of merely observing, in his most unspleasent tones, that a fellow could hardly help treading on some bit of George's foot, if he had to move about at all within ten yards of where George was sitting, suggesting that George never ought to come into an ordinary sized boat with feet that length, and advising him to hang them over the side, as he would have done before supper, now said: 'Oh, I'm sorry, old chap; I hope I haven't hurt you.'
And George said, 'Not at all'; that it was his fault; and Harris said no, it was his."
('Three men in a boat' - Jerome K. Jerome)