Quote by Miguel de Cervantes, Don Quixote

Eat not garlic nor onions, lest they find out thy boorish origin by the smell; walk slowly and speak deliberately, but not in such a way as to make it seem thou art listening to thyself, for all affectation is bad. Dine sparingly and sup more sparingly still; for the health of the whole body is forged in the workshop of the stomach. Be temperate in drinking, bearing in mind that wine in excess keeps neither secrets nor promises. Take care, Sancho, not to chew on both sides, and not to eruct in anybody's presence.Eruct! said Sancho; I don't know what that means.To eruct, Sancho, said Don Quixote, means to belch, and that is one of the filthiest words in the Spanish language, though a very expressive one; and therefore nice folk have had recourse to the Latin, and instead of belch say eruct, and instead of belches say eructations; and if some do not understand these terms it matters little, for custom will bring them into use in the course of time, so that they will be readily understood; this is the way a language is enriched; custom and the public are all-powerful there.In truth, senor, said Sancho, one of the counsels and cautions I mean to bear in mind shall be this, not to belch, for I'm constantly doing it.Eruct, Sancho, not belch, said Don Quixote.Eruct, I shall say henceforth, and I swear not to forget it, said Sancho.

Summary

This quote from Miguel de Cervantes' novel Don Quixote provides a number of satirical instructions on how to appear refined and polite. The speaker advises against consuming foods like garlic and onions that may give away one's lower social status through their smell. Walking slowly and speaking deliberately are recommended, as long as one avoids the pretense of listening to oneself. The importance of moderation in eating and drinking is emphasized for the sake of good health and the ability to keep promises. The humorous exchange about the word "eruct" (to belch) reflects the idea that language and customs evolve over time.