Understanding human nature is the highest knowledge, and only by knowing it can we know God. It is also a fact that the knowledge of God is the highest knowledge, and only by knowing God can we understand human nature.
It is good and very grand to conquer external nature, but grander still to conquer our internal nature.... This conquering of the inner man, understanding the secrets of the subtle workings that are within the human mind, and knowing its wonderful secrets, belong entirely to religion.