Here’s an interesting quote by William Walker Atkinson

“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.

The only reconciliation is to be found in the fundamental working hypothesis which holds that both Mind and Body — both Mental States and Physical Conditions—are the two aspects of something greater than either — the opposing poles of the same Reality. The radical Materialist asserts that the Body is the only reality, and that Mind is merely its “by‑product.”

The Mentalist asserts that the Mind is the only reality, and that the Body is merely its grosser form of manifestation. The unprejudiced philosopher is apt to stand aside and say: “You are both right, yet both wrong — each is stating the truth, but only the half‑truth.” With the working hypothesis that Mind and Body are but varying aspects of the Truth — that Mind is the inner essence of the Body, and Body the outward manifestation of the Mind—we find ourselves on safe ground.

We have written this book to reach not only those who refuse to see the wonderful influence of the Mental States over the Physical Conditions, but also for our “metaphysical” friends who have become so enamored with the power of the Mind that they practically ignore the existence of the Body, indeed, in some cases, actually denying the existence of the latter. We believe that there is a sane middle‑ground in “metaphysical healing,” as there is in the material treatment of disease. In this case, not only does Truth lie between the two extremes, but it is composed of the blending and assimilation of the two opposing ideas and theories.”