For the person who lives a virtuous life, of steadfastness and good judgment, happiness is always within reach - Massimo Pigliucci

Lucius Annaeus Seneca is a towering and controversial figure of antiquity. He lived from 4 BCE to 65 CE, was a Roman senator and political adviser to emperor Nero, and experienced exile but came back to Rome to become one of the wealthiest citizens of the Empire. He tried to steer Nero toward good governance, but in the process became his indirect accomplice in murderous deeds. In the end, he was ‘invited’ to commit suicide by the emperor, and did so with dignity, in the presence of his friends.

Seneca wrote a number of tragedies that directly inspired William Shakespeare but was also one of the main exponents of the Stoic school of philosophy, which has made a surprising comeback in recent years. Stoicism teaches us that the highest good in life is the pursuit of the four cardinal virtues of practical wisdom, temperance, justice, and courage – because they are the only things that always do us good and can never be used for ill. It also tells us that the key to a serene life is the realisation that some things are under our control and others are not: under our control are our values, our judgments, and the actions we choose to perform. Everything else lies outside of our control, and we should focus our attention and efforts only on the first category.

Seneca wrote a series of philosophical letters to his friend Lucilius when he was nearing the end of his life. The letters were clearly meant for publication, and represent a sort of philosophical testament for posterity. I chose letter 92, ‘On the Happy Life’because it encapsulates both the basic tenets of Stoic philosophy and some really good advice that is still valid today.

The first thing to understand about this letter is the title itself: ‘happy’ here does not have the vague modern connotation of feeling good, but is the equivalent of the Greek word eudaimonia, recently adopted also by positive psychologists, and which is best understood as a life worth living. For Seneca and the Stoics, the only life worth living is one of moral rectitude, the sort of existence we look back to at the end and can honestly say we are not ashamed of.

That said, and contrary to popular lore, the Stoics weren’t killjoys. Indeed, in his essay ‘On Tranquillity of Mind’, Seneca himself wrote:

Socrates did not blush to play with little boys, Cato used to refresh his mind with wine after he had wearied it with application to affairs of state, and Scipio would move his triumphal and soldierly limbs to the sound of music … It does good also to take walks out of doors, that our spirits may be raised and refreshed by the open air and fresh breeze: sometimes we gain strength by driving in a carriage, by travel, by change of air, or by social meals and a more generous allowance of wine: at times we ought to drink even to intoxication, not so as to drown, but merely to dip ourselves in wine: for wine washes away troubles and dislodges them from the depths of the mind, and acts as a remedy to sorrow as it does to some diseases.

Stoics are often contrasted with Epicureans, and ‘On the Happy Life’ includes passages where Seneca comments on that contrast. Epicureanism, however, should not be interpreted in the modern sense of laissez-faire hedonism (à la sex, drugs and rock’n’roll), as it actually was a philosophy of moderation aimed mostly at avoiding pain (both physical and mental) and at enjoying the simple pleasures of life (like healthy meals and good friendship).

Both the Stoics and the Epicureans valued the practice of virtue and the pleasures of life. The difference was one of the priorities: the Epicureans, for instance, withdrew from political life because it was bound to cause pain (consider the recent US elections and you might sympathise). The Stoics, by contrast, would never trade moral rectitude for either the pursuit of pleasure or the avoidance of pain.

Seneca wrote a much longer essay on the same topic of what makes for a happy life, one that includes a set of seven ‘commandments to himself’ (from book XX ‘Of a Happy Life’). They provide a way to philosophically structure our own lives:

I) I will look upon death or upon a comedy with the same expression of countenance.

II) I will despise riches when I have them as much as when I have them not.

III) I will view all lands as though they belong to me, and my own as though they belonged to all mankind.

IV) Whatever I may possess, I will neither hoard it greedily nor squander it recklessly.

V) I will do nothing because of public opinion, but everything because of conscience.

VI) I will be agreeable to my friends, gentle and mild to my foes: I will grant pardon before I am asked for it and will meet the wishes of honorable men half-way.

VII) Whenever either Nature demands my breath again, or reason bids me dismiss it, I will quit this life, calling all to witness that I have loved a good conscience and good pursuits.

• Source: Massimo Pigliucci is the K D Irani Professor of Philosophy at the City College of New York.