1 When lately we made mention of the Pharisee and the publican, and hypothetically yoked two chariots out of virtue and vice; we pointed out each truth, how great is the gain of humbleness of mind, and how great the damage of pride. For this, even when conjoined with righteousness and fastings and tithes, fell behind; while that, even when yoked with sin, out-stripped the Pharisee's pair, even although the charioteer it had was a poor one. For what was worse than the publican?
But all the same since he made his soul contrite, and called himself a sinner; which indeed he was; he surpassed the Pharisee, who had both fastings to tell of and tithes; and was removed from any vice. On account of what, and through what? Because even if he was removed from greed of gain and robbery, he had rooted over his soul the mother of all evils— vain-glory and pride. On this account Paul also exhorts and says “Let each one prove his own work; and then he will have his ground of boasting for himself, and not for the other.”
Whereas he publicly came forward as an accuser of the whole world; and said that he himself was better than all living men. And yet even if he had set himself before ten only, or if five, or if two, or if one, not even was this endurable; but as it was, he not only set himself before the whole world, but also accused all men. On this account he fell behind in the running. And just as a ship, after having run through innumerable surges, and having escaped many storms, then in the very mouth of the harbour having been dashed against some rock, loses the whole treasure which is stowed away in her— so truly did this Pharisee, after having undergone the labours of the fasting, and of all the rest of his virtue, since he did not master his tongue, in the very harbour underwent shipwreck of his cargo. For the going home from prayer, whence he ought to have derived gain, having rather been so greatly damaged, is nothing else than undergoing shipwreck in harbour.
Source: Homily Concerning "Lowliness of Mind" (New Advent)