While it's not technically on the GBWW list, Seneca's Letters fits right in with Marcus Aurelius and Epictetus. Seneca is a hard man to describe. He was a first century moral philosopher, a playwright, and a billionaire (by Roman standards). He had dealings, good and bad, with multiple Roman emperors. He wrote his Letters late in his life to a young man named Lucilius in order to help Lucilius develop as a practitioner of Stoicism.
It is important to note the word "practitioner". Unlike many philosophies, Stoicism is a philosophy that is, first and foremost, meant to be lived. It can be thought of not just as philosophy in the conventional sense but also as a toolbox for better living. Revisiting my complaint about Marcus Aurelius and sour grapes, I now realize, thanks to Seneca, that his technique of reframing things in order to become indifferent to them is not really about the actual reasoning involved. The only important thing is achieving that sense of indifference. This may seem a little intellectually dishonest. However, Stoicism asks a lot of its practitioners. It asks them to become indifferent to pleasure, bad fortune, and even death itself. Faced with such a formidable task, it is understandable that a Stoic would gladly take up any tool available.
The importance of this indifference is clear to me now, even if it is difficult to put into practice. Seneca argues that the happy life is the virtuous life. But a lot of ancient philosophers make this same claim and from many different points of view. The key to understanding the Stoic argument is understanding that you can not be consistently happy if your happiness is tied to things you can not control. This is how indifference becomes important. In the strictest sense, there is very little we can control. We can influence many things in the world and make more desirable outcomes more probable. But this control is never absolute. As such, there is always room for disappointment. There is, however, one thing that we can always control: our own choices. So if a person can become indifferent to all the uncontrollable things and care only about his own choices, achievement of the happy life begins to seem possible. You would only be left with the problem of making sure that you are happy with all of your choices. And while we regret the outcomes of many virtuous choices, it is irrational to be unhappy with the choices themselves. Thus, if you only care about your choices and you always make good choices that you can be happy about, you will have a happy life. It is a state of mind as appealing as it is difficult to reach. But that is the promise of Stoicism in a nutshell.
Seneca has also taught me a few things about the nature of fame and personal achievement. Personally, I have never been too interested in fame. I value my quiet life too much. But fame can be powerful. It can even be necessary for achieving certain goals. What kind of emperor would Marcus Aurelius be if no-one knew his name? Thankfully, I have no such goals. Though perhaps someday I will. And, hopefully, on that day, I will be able to think of fame as a mere tool. I say this because Seneca has also made it clear to me that fame is dangerous. I do not mean physically dangerous, though it can be. Instead, it is dangerous spiritually. The core of the problem is that fame is a numbers game. It requires appealing to the maximum number of people possible. And you achieve this by appealing to the middle of humanity's bell curve. And the average human is imperfect in many ways. This average human is neither particularly bright nor particularly good. As such, this human is a terrible judge of character. To appeal to this type of human in the numbers required for true fame, you will likely need to make compromises and cultivate attributes that most appeal to literal mediocrity. In a way, Seneca argues that we should aspire to become something so great that remaining appealing to the crowd would be difficult or impossible. Because of fame's natural impediment to greatness, the majority of the best and most successful people are people you have never heard of. If you want to be the best, you can not waste your time or compromise yourself trying to be recognized as the best. And if you do become the best, even if the crowd doesn't know who you are, the people who matter will be unable to ignore you.
Seneca provides some lessons on friendship that I have taken to heart as well. It is a truism, said in many forms, that we are the company we keep. Butlike many truisms, they go by us unnoticed. Seneca may have finally made it stick in my case. If you care about being good, with respect to morality or even some professional skill, do not allow yourself to fall in with those who are average or worse. Seek out exceptional souls and mind wherever you can. Appreciate them, Allow them to help you grow. And be sure to return the favor.
Seneca has probably affected me more than anything I have ever read in recent years. And there is far more wisdom in these volumes I could ever discuss here. Seneca even addresses this very problem. How do you cite the good parts of a work that is almost nothing but good parts? The only reasonable course of action is to encourage people to read the whole work themselves. Some authors Seneca would quote to Lucilius. But for truly great authors, he would send the whole book. So I urge you: Please, if you care about your own well-being, strongly consider reading some Seneca and the other Stoic authors.