When we speak of individual sins, we speak of volition and consequent action. When we speak of moral depravity as distinct from individual sinful acts, we mean that abiding and wrong, selfish choice from which these volitions proceed. Please observe the distinction I make between sinful acts and moral depravity. Moral depravity is originally a choice and therefore a mental act. It is the choice of an end, and therefore an abiding, standing choice.
Volitions are individual efforts to secure the end chosen.
Sinful acts are found in the life. Moral depravity lies back of the outward life, and back of volition, in a standing preference of self-interest over God's interests and all other interests. It is not the substance of either soul or body. He maintains this on the ground that the soul of the sinner is, in its very substance, enmity against God. But this must be a great mistake.