Here's a bit from the essay.
by Honore de Balzactranslated from the French by Robert Onopa
Coffee is a great power in my life; I have observed its effects on an epic scale. Coffee roasts your insides. Many people claim coffee inspires them, but, as everybody knows, coffee only makes boring people even more boring. Think about it: although more grocery stores in Paris are staying open until midnight, few writers are actually becoming more spiritual.
But as Brillat-Savarin has correctly observed, coffee sets the blood in motion and stimulates the muscles; it accelerates the digestive processes, chases away sleep, and gives us the capacity to engage a little longer in the exercise of our intellects. It is on this last point, in particular, that I want to add my personal experience to Brillat-Savarin's observations.
Coffee affects the diaphragm and the plexus of the stomach, from which it reaches the brain by barely perceptible radiations that escape complete analysis; that aside, we may surmise that our primary nervous flux conducts an electricity emitted by coffee when we drink it. Coffee's power changes over time. [Italian composer Gioacchino] Rossini has personally experienced some of these effects as, of course, have I. "Coffee," Rossini told me, "is an affair of fifteen or twenty days; just the right amount of time, fortunately, to write an opera." This is true. But the length of time during which one can enjoy the benefits of coffee can be extended.