In the 1100 years between Augustine and the Council of Trent, the Idea of Original Sin both changed and stayed the same.  Chapter 4 covers some highlights.

Augustine wrote at the time when the Roman Empire (now officially converted to Christianity but still very much in the ancient Pagan milieu) was decentralizing.

Anselm, writing in England around 600 years later, wrote at a time when the Roman world was remembered through fantasy, legend and ideal.

Augustine wanted to protect Christianity from a host of Pagan assimilators.

Anselm just wanted to make sense of this concept of Original Sin.

The once Pagan concept of a hierarchy of natures had been internalized.  Human faculties, powers and capacities ranged from digestive to visionary.  At the low end, human natures were “material” or “of nature”.  At the high end, human natures were “not material” or “of spirit”.

The intellect and the will were faculties “of nature”.  The “capacity for justice” on the other hand, was “of spirit”.