The soul nature of man is not determined by the body alone. Man does
not wander aimlessly and without purpose from one sensation to
another, nor does he act under the influence of every casual
incitement that plays upon him either from without or through the
processes of his body. He thinks about his perceptions and his acts.
By thinking about his perceptions he gains knowledge of things. By
thinking about his acts he introduces a reasonable coherence into his
life. He knows that he will worthily fulfill his duty as a man only
when he lets himself be guided by correct thoughts in knowing as well
as in acting. The soul of man, therefore, is confronted by a twofold
necessity. By the laws of the body it is governed by natural
necessity. It allows itself also to be governed by the laws that guide
it to exact thinking because it voluntarily acknowledges their
necessity. Nature subjects man to the laws of changing matter, but he
subjects himself to the laws of thought. By this means he makes
himself a member of a higher order than the one to which he belongs
through his body. This order is the spiritual. The spiritual is as
different from the soul as the soul is from the body. As long as only
the particles of carbon, hydrogen, nitrogen and oxygen that are in
motion in the body are spoken of, we do not have the soul in view.
Soul life begins only when within the motion of these particles the
feeling arises, I taste sweetness, or, I feel
pleasure. Likewise, we do not have the spirit in view as long
as merely those soul experiences are considered that course through
anyone who gives himself over entirely to the outer world and his
bodily life. This soul life is rather the basis of the spiritual just
as the body is the basis of the soul life. The biologist is concerned
with the body, the investigator of the soul the psychologist
with the soul, and the investigator of the spirit with the
spirit. It is incumbent on those who would understand the nature of
man by means of thinking, first to make clear to themselves through
self-reflection the difference between body, soul and spirit.