Letters from a Stoic, explained.

In his second letter to Lucilius, Seneca warned that reading many authors in a hurry leaves the mind scattered. Stay with a few great thinkers and digest them, he wrote, the way food must stay down and a plant must stay put to grow. Many of his early letters end with one saying to think over that day.

A few books, truly read, will change you more than a hundred skimmed. Practical advice: choose one book worth reading twice, and finish it before you start another.

After long travels, Seneca’s friend Lucilius was as gloomy as ever. Seneca told him he needed a change of soul, not of sky, and passed on Socrates’ reply to a man whose trips did him no good: you traveled in your own company. Settle the trouble, Seneca wrote, and any place will feel welcoming.

Wherever you go, you are the first thing you pack. Practical advice: before you book an escape, name what you are trying to leave behind.

In Letter 7, Seneca told Lucilius that crowds were the thing to avoid. He had stopped at the arena at noon, expecting light fun, and found condemned men forced to kill each other while the crowd cheered. From the games, he admitted, he came home greedier and crueler. Choose people who make you better, he wrote, and people you can help.

The company you keep comes home with you. Practical advice: notice how you feel after time with each group, and spend more evenings with the ones who leave you kinder.

In Letter 27, Seneca told of Calvisius Sabinus, a rich man with a poor memory who wanted to seem learned. He bought slaves who knew Homer, Hesiod and the lyric poets by heart, and had them feed him lines at dinner. He still stumbled mid-word. No one, Seneca wrote, can borrow or buy a sound mind.

You can hire someone to know things, but never to be wise for you. Practical advice: before you save another summary, spend ten minutes saying in your own words what the last one taught you.

In a December letter, written as Rome feasted for the Saturnalia, Seneca told his friend Lucilius to set aside a few days for the cheapest food, a hard bed and rough clothes, and to ask if this was what he had feared. Soldiers drill in peacetime, he said, and Epicurus tested himself on less than a penny.

Practice the hard times while the good times last. Practical advice: live on a lean budget for one week, and notice how much of the fear was only fear.

In 64 AD, fire destroyed Lugdunum, today’s Lyon, in what Seneca called a single night. Writing about their shaken friend Liberalis, he said the unexpected weighs heaviest, so think about what can happen, not only what usually does. Tacitus says Nero sent the city four million sesterces to rebuild.

You can’t stop every loss, but you can take out the surprise. Practical advice: once a season, ask calmly what could change overnight, and do one small thing to be ready.

When Lucilius’s slaves ran away while he was busy with work, Seneca told him this was ordinary life: things get thrown at you, as in a crowd or on a road. Bear what you cannot change without railing. He ended with a prayer by the Stoic Cleanthes, put into Latin: Fate leads the willing and drags the unwilling.

You will go either way, so choose to walk. Practical advice: when something is decided and final, spend your strength on the next step, not the argument.

When Lucilius lost his friend Flaccus, Seneca wrote that tears are allowed, as long as they do not overflow. His teacher Attalus compared the memory of lost friends to old wine, bitter and pleasant at once. Seneca admitted he had wept past his own rules for his younger friend Serenus.

Love your friends greedily while they are here, and let them come back gladly when they are gone. Practical advice: when you miss someone, tell one of their stories out loud.

Soon after leaving Nero’s court, Seneca heard from Lucilius, who sent a letter by a man he called a friend, then warned Seneca not to tell him everything. Seneca’s answer, after Theophrastus: judge a person before you make them a friend, then trust them as you trust yourself. He did that with Lucilius, sharing even his illness and his faults.

Take your time letting someone in, then let them all the way in. Practical advice: before you share something private with someone new, watch how they keep other people’s secrets.

In his ninth letter, Seneca answered Epicurus, who said a wise man needs friends to look after him when he is sick or in trouble. Seneca turned it around: a wise man wants friends so that he can look after them. Friends made for gain leave when the gain does. To make friends, he passed on Hecato’s love potion: if you would be loved, love.

If you want to be loved, go first and love. Practical advice: this week, do one kind thing for someone you’d like to know better.

Closing his eleventh letter, Seneca passed on Epicurus’s advice: keep a person of good character before your eyes, and live as if they were watching. Choose a Cato, he said, or the gentler Laelius. Romans told how a crowd at the games of Flora was too ashamed to misbehave while Cato the Younger sat watching.

Live as if someone good were watching, until you become that someone. Practical advice: pick one person whose respect you want, and picture them before a hard choice.

In Letter 47, Seneca, a slave owner himself, praised Lucilius for living on friendly terms with his slaves, and called them men, not just slaves. He described slaves standing hungry and silent through a master’s dinner, and a master who sold Callistus, then waited at his door in vain. He never called for slavery to end.

Treat the people below you the way you’d want those above you to treat you. Practical advice: learn the name of someone who serves you often, and use it.