Doubtless this is the hardest of all struggles, because by fighting against ourselves, we are, at the same time, attacked by ourselves, and on that account the victory obtained in such a conflict will be of all others the most glorious and most dear to God.
Therefore, if you used every endeavour to mortify yourself, and to tread down your inordinate affections, inclinations, and rebellious passions, even in the smallest matters, you would be rendering to God a far greater and more acceptable service, than if whilst permitting some of your inclinations to remain unmortified, you scourged yourself until you bled, fasted more rigorously, and practised an austerity greater than that of the hermits and saints of the desert, or converted souls by thousands.
For, although in itself the conversion of souls is dearer to God than the mortification of an irregular desire, yet it is not your duty to will and perform that which is in itself more excellent, but that which God before all else strictly desires and requires of you. For He doubtless seeks and desires of you self-conquest, and the thorough mortification of your passions, rather than that you, wilfully leaving one of them alive in you, should perform in some other direction some greater and more notable service for His sake.
Now you see wherein the real perfection of a