History is strewn with examples of slavery, indentured servants and other forms of servitude. While many snap to America when they think of slavery, it's wise to remember this was not the only form practiced in humanity's history. In fact the practice still survives today, in 2021, as practiced by government of China (Communist Party of China); see here and here for recent reports or search for "Muslim Uyghurs China" to see many other harrowing reports.
The Romans during Seneca's time were not exempt from this moral failing. It seems that Seneca at least recognized the need to be as kind as possible if one were to own slaves or have servants. In this context, Seneca writes this letter to Lucilius.
So what are we to learn from this letter, if we live in a society where slavery is outlawed? Can we glean something applicable to us? There are a few things from the letter we can consider.
Treat everyone as humans, comrades, friends and fellow slaves (see first paragraph of letter).
Masters and those who lord over us, in some cases, are slaves to their own passions.
The master eats more than he can hold, and with monstrous greed loads his belly until it is stretched and at length ceases to do the work of a belly; so that he is at greater pains to discharge all the food than he was to stuff it down.
We all come from the same genetic root; we are all brothers and sisters.
Kindly remember that he whom you call your slave sprang from the same stock, is smiled upon by the same skies, and on equal terms with yourself breathes, lives, and dies.
If you ever find yourself looking down upon someone else, for example, a homeless person or someone who suffers from addiction, stop and consider that your lot may become like theirs' some day. Therefore, treat everyone with kindness and service. Treat others as you would want to be treated.
But this is the kernel of my advice: Treat your inferiors as you would be treated by your betters. And as often as you reflect how much power you have over a slave, remember that your master has just as much power over you. "But I have no master," you say. You are still young; perhaps you will have one.
Your character and attitude is in your control; but your fate largely is not.
Each man acquires his character for himself, but accident assigns his duties.
If there are those in your circle of influence who need education, strive to educate and mentor them. We are all striving to help each other. Too many today close themselves off from society; they build up walls and post security guards around their mansions and send their children to private schools. If we are to elevate society as a whole, we must not segregate. I fear we are rapidly segregating and losing the ability to learn from others as well as to help others.
if there is any slavish quality in them as the result of their low associations, it will be shaken off by intercourse with men of gentler breeding.
Be a mentor.
Good material often stands idle for want of an artist.
Don't judge a person by looks or title only.
doubly a fool who values a man from his clothes or from his rank.
Contemplate who your own master is. We are all slaves in one form or fashion; and many times we possess the key to unlock the chains and free ourselves, but often we choose not to.
Show me a man who is not a slave; one is a slave to lust, another to greed, another to ambition, and all men are slaves to fear. I will name you an ex-consul who is slave to an old hag, a millionaire who is slave to a serving-maid; I will show you youths of the noblest birth in serfdom to pantomime players! No servitude is more disgraceful than that which is self-imposed.
Mark what angers you; there you will find your master.
That which annoys us does not necessarily injure us; but we are driven into wild rage by our luxurious lives, so that whatever does not answer our whims arouses our anger.