Reason, Formal Cause, Body

According to Aristotle, as opposed to Descartes, Reason is not the only part of the Soul.  Thus, according to the former but not the latter, the Body can be influenced by causes other than Reason.  These are inner organic causes, that are parts of the non-Rational parts of the Soul--the Nutritive and the Locomotive parts, i. e. processes that strengthen the Body, and processes that secures the sources of strengthening.  Now, Reason can influence these processes, by improving nutritional processes, and by making the Locomotion that secures them more efficient.  But it is by imposing Balance on the Body, via the principle of Golden Mean, that Reason functions as a Formal Cause on the Matter of the Body.