[z3n]

"3. In one way the devil is the cause of every human sin; he tempted Adam and thus contributed to the fall which renders men prone to sin. But, in a strict sense, diabolical influence does not enter into every sin of man. Some sins come of the weakness of human nature and from inordinateness of appetites which the sinner freely allows to prevail."

I would like some clarity between how "prone to sin" (resulting from the fall) is different than "weakkness of human nature..."

[stfassisi]

“”I would like some clarity between how “prone to sin” (resulting from the fall) is different than “weakkness of human nature...”””

Here is more from Saint Aquinas on this...

“The devil is the occasional and indirect cause of all our sins, in so far as he induced the first man to sin, by reason of whose sin human nature is so infected, that we are all prone to sin: even as the burning of wood might be imputed to the man who dried the wood so as to make it easily inflammable. He is not, however, the direct cause of all the sins of men, as though each were the result of his suggestion. Origen proves this (Peri Archon iii, 2) from the fact that even if the devil were no more, men would still have the desire for food, sexual pleasures and the like; which desire might be inordinate, unless it were subordinate to reason, a matter that is subject to the free-will” (STh I-II, Q. 80 Art. 4).

Human Nature can be weak due to food ,sex etc...