Purity of life is the central theme of all the religions which have been given through the ages to humanity. For purity is not only a religious idea but it is the outcome of the nature of life itself, and one sees it in some form or other in every living creature. It is the tendency of all animals and birds to cleanse their coats or feathers, and to find a clean place in which to live or sit; and in the human being this tendency is even more pronounced. Even a man who has not risen above the material life shows this faculty in physical cleanliness, but behind this there is something else hidden, something which is the secret of the whole creation and the reason why the world was made.