William Walker Atkinson 
Mind and Body, or Mental States and Physical Conditions 

Excerpt: "Mind and Body-Mental States and Physical Conditions! To the mind of those who have contented themselves with merely the superficial aspects of things, these two things-mind and body; and mental states and physical conditions-seem to be as far apart as the two poles; seem to be opposites and contradictories impossible of reconciliation. But to those who have penetrated beneath the surface of things, these two apparent opposites are seen to be so closely related and inter-related-so blended and mingled together in manifestation-that it is practically impossible to scientifically determine where the one leaves off and the other begins. And so constant and close is their mutual action and reaction, that it often becomes impossible to state positively which is the cause and which the effect."