This Lower Nature
Nicolas Berdyaev describes the flesh with great accuracy:
This lower nature, when it occupies its proper place in the hierarchy of the universe, is not in itself evil, for it belongs to the divine world. It is only when it usurps the place of something higher that it become untrue to itself and an evil. Animal nature certainly has its place in the scale of values and an eternal destiny; but when it takes possession of man, when man submits his spirit to the control of the lower element, then it does indeed become an evil thing. For evil is a question of the direction pursued by the spirit, not of the constitution of nature itself.
Source: Dallas Willard, The Spirit Of The Disciplines, p.87.