The Institutes, Book 12
Pride Destroys Every Virtue
There is no other fault so destructive of all the virtues, none that so robs and strips a man of all righteousness and holiness, as this evil of pride. Like some plague it attacks the whole man. Not content to damage one part or one limb only, it injures the whole body by its deadly influence, and tries to cast down by a most fatal fall and to destroy those who were already at the top of the tree of the virtues.
Every other fault is satisfied within its own bounds and limits. Though it clouds other virtues as well, it is aimed mainly against one, and attacks and assaults that one in particular. To make my meaning clearer: gluttony, that is, the appetites of the belly and the pleasures of the palate, destroys strict self-control; lust stains purity; anger destroys patience. So sometimes a man who is enslaved to some one sin is not altogether lacking in other virtues. Robbed only of the one virtue that gives way in the struggle to the vice that is its rival and opposite, he can to some extent keep his other virtues. But once this one has taken possession of some unhappy soul, it is like a most brutal tyrant that has captured the lofty citadel of the virtues: it utterly destroys and lays waste the whole city. It levels the once high walls of holiness to the ground of the vices and throws them down in confusion, and it lets no shadow of freedom survive any longer in the soul subject to it. The richer that soul was at first, the heavier will be the yoke of slavery by which, in its cruel ravages, it strips the conquered soul of all its powers of virtue.