Nicene and Post-Nicene Fathers, Ser. II, Vol. XI:
The Works of John Cassian.: Chapter V. Of the faults which are contracted through our own fault, without natural impulses.

Chapter V.

Of the faults which are contracted through our own fault, without natural impulses.

But we affirm that some faults grow up without any natural occasion giving birth to them, but simply from the free choice of a corrupt and evil will, as envy and this very sin of covetousness; which are caught (so to speak) from without, having no origination in us from natural instincts. But these, in proportion as they are easily guarded against and readily avoided, just so do they make wretched the mind that they have got hold of and seized, and hardly do they suffer it to get at the remedies which would cure it: either because these who are wounded by persons whom they might either have ignored, or avoided, or easily overcome, do not deserve to be healed by a speedy cure, or else because, having laid the foundations badly, they are unworthy to raise an edifice of virtue and reach the summit of perfection.