The taboo against nakedness is an obstacle to a decent attitude on the subject of sex. Where young children are concerned, this is now recognized by many people. It is good for children to see each other and their parents naked whenever it so happens naturally. There will be a short period, probably at about three years old, when the child is interested in the difference between his father and his mother, and compares them with the differences between himself and his sister, but this period is soon over, and after this he takes no more interest in nudity than in clothes. So long as parents are unwilling to be seen naked by their children, the children will necessarily have a sense that there is a mystery, and having that sense they will become prurient and indecent. There is only one way to avoid indecency, and that is to avoid mystery. There are also many important grounds of health in favor of nudity in suitable circumstances, such as out of doors in sunny weather. Sunshine on the bare skin has an exceedingly health-giving effect.
Moreover, anyone who has watched children running about in the open air without clothes must have been struck by the fact that they hold themselves much better and move more freely and more gracefully than when they are dressed. The same thing is true of grown-up people. The proper place for nudity is out of doors in the sunshine and in the water. If our conventions allowed of this, it would soon cease to make any sexual appeal; we should all hold ourselves better, we should be healthier from the contact of air and sun with the skin, and our standards of beauty would more nearly coincide with standards of health, since they would concern themselves with the body and its carriage, not only with the face. In this respect the practice of the Greeks was to be commended.
—From Marriage and Morals (1929) by Bertrand Russell