We found it a regrettable thing that the existence of the sexual instinct in children has been denied and that the sexual manifestations not infrequently to be observed in children have been described as irregularities. It seemed to us on the contrary that children bring germs of sexual activity with them into the world, that they already enjoy sexual satisfaction when they begin to take nourishment and that they persistently seek to repeat the experience in the familiar activity of "thumb sucking."
Sigmund Freud, 1905
Sexuality takes form with the infant's earliest experiences of satisfaction. We desire to repeat the pleasure, to find again the feeling of gratification. This is what Freud meant when he wrote that "every finding of an object is in fact a refinding of it." Childhood desires often reappear disguised but with great force in adulthood.