One of the words to which the term "Sufi" is related is the Greek Sophia, meaning wisdom; wisdom which is a knowledge acquired both from within and without. Therefore Sufism is not only an intuitive knowledge nor is it only a knowledge acquired from the outer life of the world. Sufism in itself is not a religion nor even a cult with a distinct or definite doctrine. No better explanation of Sufism can be given than by saying that any person who has a knowledge of both outer and inner life is a Sufi. Thus there has never in any period of the world's history been a founder of Sufism, yet Sufism has existed at all times.