Man is the creation made for cleaving to G-d Blessed be He, and he is placed between perfection and deficiency, and it is in his hand to establish perfection. But he needs to do it out of free will and out of desire, since being forced to attain perfection wouldn't be perfection at all, and the Higher Will wouldn't be fulfilled thereby. Therefore it has to come from free will, that man will be drawn to both sides, with the ability to exercise free will, to know and want which side he chooses. Therefore man is created with what we call a good inclination (Yetzer Tov) and a bad inclination (Yetzer Hara).
But to achieve this perfection properly, in G-d's Wisdom man is made of two opposites, an intellectual soul that is pure, and an earthly body that is unenlightened. Each accordingly is drawn to its nature, the body to the material, the soul to the intellectual. A battle ensues between them. In the scenario where the soul prevails in this battle, the soul is elevated and the body is elevated along with it, and the individual attains the destined perfection. If he lets the material win out, however, then besides lowering his body, his soul also falls. He becomes unworthy of the perfection he was capable of, and it becomes unattainable, G-d Forbid. This man still has the ability to subjugate the physical to his soul and intellect and thereby attain perfection he was destined to have.
- Taken from Luzzato Derech Hashem - The Way of G-d pg 44-46 Feldheim