Why is the world called an illusion by the mystics? For the very reason that I the nature of manifestation is such that it envelops its own secret in itself, and stands out in such a rigid form that the fineness and the beauty and the mystery of its character are hidden within itself, and therefore the seekers after the truth of life, the students of life, strike two opposite paths. One wishes to learn from its external appearance; the other wishes to find out the secret which is hidden behind it. The one who learns from the external gets the knowledge of the external, which we call science. The one who finds out from within, that which is hidden within the manifestation, he is the mystic. The knowledge he gains is mysticism.