It became customary to gather in front of the Huts or around a large Tree: song and dance, true children of love and leisure, became the amusement or rather the occupation of idle men and women gathered together. Everyone began to look at everyone else and to wish to be looked at himself, and public esteem acquired a price. The one who sang or danced best; the handsomest, the strongest, the most skillful, or the most eloquent came to be the most highly regarded, and this was the first step towards inequality and vice: from these first preferences arose vanity and contempt on the one hand, shame and envy on the other; and the fermentation caused by these new leavens eventually produced compounds fatal to happiness and innocence.
This quotation represents the moment at which the balance tips in favor of amour propre. Leisure, which is harmless to the savage, who is happy merely to be idle, becomes dangerous when it is used for an activity that encourages comparison. First you need people to dance with, which is a pleasurable activity; soon, however, you will need people merely to watch you dance, to admire and compare themselves to you. Once this is the case, the evil passions released cannot be reversed. It is striking that Rousseau locates the beginning of vice in the village dance, which is largely seen as a positive event that strengthens community feeling. Rousseau would sympathize, one feels, with the puritan who didn't like sex because it might lead to dancing.