Temperance is here considered as one of the four cardinal virtues. It may be defined as the righteous habit which makes a man govern his natural appetite for pleasures of the senses in accordance with the norm prescribed by reason. In one sense temperance may be regarded as a characteristic of all the moral virtues; the moderation it enjoins is central to each of them. It is also according to St. Thomas (II-II:141:2) a special virtue. Thus, it is the virtue which bridles concupiscence or which controls the yearning for pleasures and delights which most powerfully attract the human heart. Catholic Encyclopedia
Whereby are given unto us exceeding great and precious promises: that by these ye might be partakers of the divine nature, having escaped the corruption that is in the world through lust. And beside this, giving all diligence, add to your faith virtue; and to virtue knowledge; And to knowledge temperance; and to temperance patience; and to patience godliness; And to godliness brotherly kindness; and to brotherly kindness charity. For if these things be in you, and abound, they make you that ye shall neither be barren nor unfruitful in the knowledge of our Lord Jesus Christ. But he that lacketh these things is blind, and cannot see afar off, and hath forgotten that he was purged from his old sins. 2 Peter 4:1-9
First, then, let us consider temperance, which promises us a kind of integrity and incorruption in the love by which we are united to God. The office of temperance is in restraining and quieting the passions which make us pant for those things which turn us away from the laws of God and from the enjoyment of His goodness, that is, in a word, from the happy life. Augustine, Of the Morals of the Catholic Church, chapter 19
Temperance may be the least valued of the virtues. On the face of it, it might seem rather dull. When Shakespeare wrote, "Thou art more temperate and more lovely," I can't imagine his beloved saying, "Oh thank you! I've always wanted someone to notice how temperate I am!" It's not active, doesn't require great deeds, but rather, the strength to not act when our passions are inciting us to imprudent or sinful action. Without temperance even our virtues can become disordered. We give to those who would be better off without what we're giving. Our mercy is channeled in the wrong direction. Our charity becomes obsession.
Giotto's Temperance has a quiet and peaceful sturdiness. She has an almost shrewd expression, as though she is carefully calculating the wisdom of some considered course. As I looked closely at her face, I thought, "What is going on around her mouth?" If you go to the Web Gallery of Art and enlarge her picture, you can see that her mouth is bound in some way. It reminds me of Psalm 141, "Set a guard, LORD, before my mouth, keep watch over the door of my lips" On the Getty Images site, this is described as a bridle, and I think that must be it. Temperance bridles her tongue, exhibiting a wisdom which our world desperately needs. A wisdom that I desperately need. She has a sword, and she will use it, but it, too, is bound. No hasty slicing off the soldier's ear for her. She weighs the result of her deeds.
The inscription below her feet is all but obliterated. The only word I can make out is Temperentia, but maybe that's all we need.