Everything requires for its existence its own opposite, or else it fades into nothingness. the ego needs the self and vice versa. The changing relations between these two entities constitute a field of experience which Eastern introspection has exploited to a degree almost unattainable to Western man. The philosophy of the East, although so vastly different from ours, could be an inestimable treasure for us too; but, in order to posses it, we must first earn it.
--C.G. Jung, "The Holy Men of India,"
Collected Works, vol. 11, para. 961.