But, it is possible, Aquinas says, that this diminution is done by proportion rather than subtraction. That is, man's nature could be affected in that half of it is taken with each sin. In this way, man's nature could be reduced with each sin and yet never disappear. The true importance of this point lies in Aquinas' message of hope for even the most heartless of sinners. There is always hope since even the vilest sinner does not completely lose his natural inclination to virtue.
Sin serves as an obstacle to that inclination, but it can be overcome.