Hungry and thirsty after a long walk, obliged by theory and habit to take his meals at regular times even when traveling, he enters a crowded tavern in search of dinner. From hunks of beef which hang from the rafters, the tavern's clientele cut strips of meat which they cover with butter before consuming avidly. Only partially dispelled through the open windows, the smell of strong tobacco fills the air.

He dislikes the scene. The Dutch, it seemed, were always eating, and his own self-proscribed diet of roots and fruits and eggs, guarantees, he hopes, of a long life and ascetic compensation for the absence of French cuisine, seems to him Lenten fare compared to the "overload" guzzled all around him: the loaves of rye, the salmon, mussels, shrimp, the fruit breads, chicken, veal, onions, parsnips, nuts, herring, lemons, cup after cup of tea and coffee, and tankard after tankard of  Rhenish and ale. In his excellent Dutch, he asks for an omelet made from eggs hatched eight to ten days ago but is rebuffed by an uncomprehending tavernkeeper. He orders turnips, a pear, plums, an apple, cheese, and a little wine.

More than just the gross needs of the stomach, he notes with passing curiosity, are being satisfied around him. In the corner of the tavern, a man pulls playfully at a woman's skirt, hoisting it above her knees, inspired by her seductive laughter.

He is thinking of an experiment he performed three or four years before and the discovery that resulted, one of which he is most proud. He had acquired from a slaughterhouse in Amsterdam the eye of an ox. In the back of it he cut away the membrane and replaced it with paper. When he then held the eye up to the light he witnessed, as he expected to, a small image of his room displayed on the paper--but upside down! How absurd, he had thought then, to base our knowledge of external things on a likeness so ephemeral and so comic. He vowed never to trust again in the deceptions of the visible. He placed himself ever on guard against illusion.

He reminds himself of the provisional morality, the temporary housing, he had constructed for himself years before, rules developed to guide his dealings with men not as devoted as he to the discovery of truth. He repeats them to himself: to always obey, however irrational they may seem, the laws and customs of the country in which he finds himself; to be firm and resolute in his actions, imitating (as he had once written) "those travelers who, finding themselves lost in some forest, [do] not wander about by heading first this way and then another way, nor still less remain in one place, but . . . instead always walk as straight as they can in the same direction"; to seek control of himself rather than fortune; to dedicate his life to development of his reason. His ethic soothes him.