Restrain inordinate passions and impulses.
Self-control is a moral disposition that strengthens the will, enabling it to resist the inordinate impulses and desires that arise from passion and emotion. Both self-control and moderation effectively govern desire, but self-control achieves this through acts of the will, whereas moderation is a habitual tendency of the passions themselves toward reasonable goods. The disposition of self-control, therefore, is a great aid to the acquisition and preservation of moderation and the other virtues, though it does not attain to the same level of moral excellence.
