John Cassian quotes
Our third conflict is against covetousness which we can describe as the love of money; a foreign warfare, and one outside of our nature. ... For the rest of the incitements to sin planted in human nature seem to have their commencement as it were congenital with us, and somehow being deeply rooted in our flesh, and almost cœval with our birth, anticipate our powers of discerning good and evil, and although in very early days they attack a man, yet they are overcome with a long struggle.But this disease coming upon us at a later period, and approaching the soul from without, as it can be the more easily guarded against and resisted, so, if it is disregarded and once allowed to gain an entrance into the heart, is the more dangerous to every one, and with the greater difficulty expelled. For it becomes "a root of all evils" [1 Timothy 6:10] and gives rise to a multiplicity of incitements to sin.
John Cassian