This is an unusual letter. Has Lucilius made an oath to philosophy? Seneca states at the beginning of the letter:
You have promised to be a good man; you have enlisted under oath; that is the strongest chain which will hold you to a sound understanding.
He further elaborates that the oath is the same one as a gladiator.
The words of this most honourable compact are the same as the words of that most disgraceful one, to wit: "Through burning, imprisonment, or death by the sword."
Then Seneca confidently states that while a gladiator has the option to beg for pity from the crowd, the Stoic does not enjoy the same luxury. The Stoic must face daily life and death with equanimity:
The gladiator may lower his weapon and test the pity of the people; but you will neither lower your weapon nor beg for life. You must die erect and unyielding. Moreover, what profit is it to gain a few days or a few years? There is no discharge for us from the moment we are born.
The path to freedom and other benefits is philosophy.
Betake yourself therefore to philosophy if you would be safe, untroubled, happy, in fine, if you wish to be, – and that is most important, – free.
Free from what? Passions. Philosophy will teach you to be free from passions instead of being driven by them.
These passions, which are heavy taskmasters, sometimes ruling by turns, and sometimes together, can be banished from you by wisdom, which is the only real freedom. There is but one path leading thither, and it is a straight path; you will not go astray. Proceed with steady step, and if you would have all things under your control, put yourself under the control of reason.
Many people give into their passions and do not lead a life of reason. As they are driven more and more by their passions, they become lost. Until, one day, they wake up and ask themselves, 'how?'
It is disgraceful ... to be carried along, and then suddenly, amid the whirlpool of events, to ask in a dazed way: "How did I get into this condition?"