Among the young, digestion is often accompanied by a slight shivering, and among the old, by a strong desire for sleep.
In the former case, Nature is withdrawing the heat from the surface to make use of it in her laboratory ; in the latter, the same motive power, weakened by age, is unable to cope with the labour of digestion and the stimulation of the senses at one and the same time.
In the initial stages of digestion, it is dangerous to engage in mental activity, and more dangerous still to indulge the cravings of the flesh. Hundreds of men are carried away every year down the stream which flows to the graveyards of the capital, because after dining well, and sometimes by reason of dining too well, they have not been able to shut their eyes and stop up their ears.
John Cale: Guts (Spanish TV Link)
Text: Jean-Anthelme Brillat-Savarin, The Philosopher in the Kitchen, tr. Anne Drayton, New York, Penguin, 1970.