John Cassian, The Institutes VII.6: How difficult the evil of covetousness is to drive away when once it has been admitted

Wherefore let not this evil seem of no account or unimportant to anybody: for as it can easily be avoided, so if it has once got hold of any one, it scarcely suffers him to get at the remedies for curing it. For it is a regular nest of sins, and a “root of all kinds of evil,” and becomes a hopeless incitement to wickedness, as the Apostle says, “Covetousness,” i.e. the love of money, “is a root of all kinds of evil.”