The state coffee puts one in when it is drunk on an empty stomach under these magisterial conditions produces a kind of animation that looks like anger: one’s voice rises, one’s gestures suggest unhealthy impatience: one wants everything to proceed with the speed of ideas; one becomes brusque, ill-tempered about nothing. One actually becomes that fickle character, The Poet, condemned by grocers and their like. One assumes that everyone is equally lucid.
A man of spirit must therefore avoid going out in public. I discovered this singular state through a series of accidents that made me lose, without any effort, the ecstasy I had been feeling. Some friends, with whom I had gone out to the country, witnessed me arguing about everything, haranguing with monumental bad faith. The following day I recognized my wrongdoing and we searched the cause. My friends were wise men of the first rank, and we found the problem soon enough: coffee wanted its victim.
— Honore de Balzac: The Pleasures and Pains of Coffee