Seneca does not support various ways of living because, he argues, these ways are not according to Nature.
Here is the list:
- sleeping in well into the morning or afternoon
- staying up all night
- basking in wine and perfumes
- being idle; becoming fat, lackadaisical and flabby
- indulging in pleasure
- drinking alcohol on an empty stomach to feel the effects more strongly
- craving food out of season; wanting flowers in winter
- putting toilets over the sea
- not swimming unless the water is heated
- desiring notoriety, peculiarity and luxury
- wanting to be the center of gossip and attention
To a modern reader, and to the aspiring modern Stoic, I would suggest we not get hung up on the specific examples, but reflect on the intent and principal of what Seneca is trying to convey.
He proposes there are ways of living according to Nature, but it is humans who wish to go around Nature or even oppose it, who are indulging in vice.
[They who] desire all things in opposition to the ways of Nature, they end by entirely abandoning the ways of Nature.
And he writes that living according to Nature is simple and straight-forward, but there are some who are "squeamish" at this plainness.
The method of maintaining righteousness is simple; the method of maintaining wickedness is complicated, and has infinite opportunity to swerve. And the same holds true of character; if you follow nature, character is easy to manage, free, and with very slight shades of difference; but the sort of person I have mentioned possesses badly warped character, out of harmony with all things, including himself. The chief cause, however, of this disease seems to me to be a squeamish revolt from the normal existence.
He ties living simply with having a good character. A good character will focus solely on the virtues and duty. Whereas, the bad character will wish to avoid duty and will want to pursue something novel, new, fanciful and fleeting.
I'll conclude with one more quote from the letter. This one reflects the Stoic pursuit to understand Nature as it is, and then to follow it. But to not follow Nature as it functions, is to turn to vice.
All vices rebel against Nature; they all abandon the appointed order. It is the motto of luxury to enjoy what is unusual, and not only to depart from that which is right, but to leave it as far behind as possible, and finally even take a stand in opposition thereto.