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If you are a regular reader of this column or have studied the science of happiness elsewhere, you’ll know that getting happier requires three kinds of effort: using your intellect to understand your emotions and impulses, building conscious habits that create well-being, and sticking to these habits, notwithstanding your short-term urges. Another way of saying this is that you need to pay attention to your passions, intellect, and will.

That might seem a fairly modern insight, but it isn’t at all. Arguably, it was devised by the medieval philosopher Thomas Aquinas, who died in 1274. Aquinas was a monk of the Dominican Order and a polymath who spread the works of Aristotle to medieval audiences. Aquinas was so prolific in his scholarship that he is said to have dictated multiple books simultaneously to his fellow monks. Among his many subjects was human happiness.

Aquinas wrote that “the final happiness of man does not consist in anything short of the contemplation of God”—a belief you might expect from a Catholic friar, that true and perfect contentment comes only when you die, go to heaven, and meet the creator. But Aquinas recognized that humans care about their life on Earth too, and he spent a lot of time thinking and writing about the “imperfect happiness” that we should strive for in the here and now. What he came up with—part of a body of insights known as Thomism—is as fresh and useful today as it was all those centuries ago. And this turns out to be all the more salient because his wisdom accords so well with modern science.

Aquinas had a monastic penchant for understatement. “In the present life,” he wrote, “we fall short of perfect happiness.” Latter-day researchers have verified this in many ways. Three scholars showed in 2015 that, on average, people judged their emotional state as positive 41 percent of the time, negative 16 percent of the time, and mixed 33 percent of the time (for the remaining 10 percent, their emotions could not be identified). Negative emotions, which militate against “perfect happiness,” are in fact perfectly normal and part of a healthy, functioning limbic system.

[Arthur C. Brooks: What monastic mystics got right about life]

The key to realizing greater happiness is not to try to eliminate one’s suffering but to manage it within reasonable levels and accentuate the many positive aspects of life. Aquinas devised a formula for achieving this, part of which includes “an operation of the practical intellect directing human actions and passions.” In everyday terms, that means developing a conscious understanding of what he called “appetitive” impulses: our animal urges and strong emotions.

Aquinas did not argue that these cravings and passions are bad. No gnostic or puritan, he believed that God created our passions. Rather, Aquinas suggested that we should govern our appetites instead of being governed by them. Doing so isn’t simple or easy, because we have powerful hedonic drives and potent feelings. But behavioral scientists have shown that simple conscious awareness and acknowledgment of these impulses can help with impulse control. This may make our short-term urges (smoking a cigarette, say) less likely to inhibit progress toward a long-term goal (achieving better health).

In other words, passions can benefit happiness as long as they are under the scrutiny of Aquinas’s second ingredient for earthly happiness: intellect. This is not simply a one-way relationship: When we use reason to manage our passions and cultivate them to accentuate their positive effect, they can stimulate the intellect as well. The process is interdependent, as Aquinas writes: “The operation of the intellect demands a previous operation of the senses.” Centuries later, this mechanism was found to be empirically true. In one 2025 study of Chinese and Iranian college students, positive emotions such as hope, pride, and enjoyment predicted greater academic engagement (measured by vigor, dedication, and absorption).

The relationship between passion and intellect involves being aware of one’s feelings and urges, and using that consciousness to decide to favor the positive, generative passions. This challenging course—take it from a former smoker—leads to the third element of Aquinas’s formula: will. This determination is the governing force that says: Choose this good thing that leads to what I want in the long run, not that bad thing that I crave in this instant. Our Dominican friend believed that humans are endowed by God with a “supernatural gift” to select what their intellect—properly directed by what Aquinas called “understanding”—has identified as the better option.

Whether willpower is supernatural or not, it can certainly be fostered and strengthened through practice, to enhance self-control. Social-science experiments show that when people strive to meet long-term goals, their willpower increases. In addition, people with greater willpower to get happier do, indeed, become happier. Not for nothing a professor at the University of Paris, Aquinas was spot on.

You might imagine that the professor was a bit of an elitist, what with his emphasis on intellect. But no, he defined intellect not as the capacity to ace the SATs but as the willingness and ability to contemplate and appreciate divine truth independently of our mortal brainpower. Aquinas thought that a person of any intelligence level could attain this kind of intellect.

Aquinas’s strategy for happiness on Earth—imperfect as that happiness may be—provides a remarkably clear blueprint for living, one that follows the best modern behavioral science. Here are three things to keep in mind as you adopt a Thomistic happiness strategy.

1. Knowledge is power. Our modern world tends to valorize emotional spontaneity and authenticity, indulging our every limbic whim. Some people celebrate this, but it would have shocked Aquinas, who strongly advocated for temperance and modesty. He was not an advocate of being a repressed individual or maintaining a stiff-upper-lip approach to life, but he did believe in acquiring a serious self-understanding (what I have previously described as “metacognition”). Become a student of yourself: your habits, desires, drives, and emotional tendencies. Many meditation and prayer techniques help with this study of self, as does journaling and some forms of therapy. Know thyself well.

2. Not all passions are equal. Once you know yourself or are getting to know yourself, you will find that some passions are morally and practically superior to others. You don’t want to become as coolly dispassionate as Mr. Spock on Star Trek; you want to be someone who is discriminating about their own tendencies, encouraging some and discouraging others. For example, you might see your natural curiosity and penchant for learning as something to be strongly encouraged to roam freely, whereas your urge to, say, shoplift might be something to try hard to avoid. Make an inventory of your passions, and decide which is which.

[Arthur C. Brooks: How to stop self-obsessing and be happier]

3. Use your willpower for positive change. The last step is to deploy your self-control strategically based on this inventory. Psychologists have demonstrated in experiments that willpower is like a muscle: Although it can be strengthened over time, in the short run, it can be easily depleted. So you need to spend your resources of willpower on the highest-priority targets. These should be your most positive and most negative passions, and you should aim to increase the former and avoid the latter.

For Aquinas, this strategy for imperfect happiness was not just theoretical. We all have our passions and impulses, and he himself was no exception. As a young man, he faced a true dilemma: whether to seek prestige or piety. The decision he made offers a master class in passion subordinated to the intellect and governed by the will.