In his Letters, Seneca exhorts us to live according to nature:
1. I commend you and rejoice in the fact that you are persistent in your studies, and that, putting all else aside, you make it each day your endeavor to become a better man. I do not merely exhort you to keep at it; I actually beg you to do so. I warn you, however, not to act after the fashion of those who desire to be conspicuous rather than to improve, by doing things which will rouse comment as regards your dress or general way of living.
2. Repellent attire, unkempt hair, slovenly beard, open scorn of silver dishes, a couch on the bare earth, and any other perverted forms of self-display, are to be avoided. The mere name of philosophy, however quietly pursued, is an object of sufficient scorn; and what would happen if we should begin to separate ourselves from the customs of our fellow-men? Inwardly, we ought to be different in all respects, but our exterior should conform to society.
3. Do not wear too fine, nor yet too frowzy, a toga. One needs no silver plate, encrusted and embossed in solid gold; but we should not believe the lack of silver and gold to be proof of the simple life. Let us try to maintain a higher standard of life than that of the multitude, but not a contrary standard; otherwise, we shall frighten away and repel the very persons whom we are trying to improve. We also bring it about that they are unwilling to imitate us in anything, because they are afraid lest they might be compelled to imitate us in everything.
4. The first thing which philosophy undertakes to give is fellow-feeling with all men; in other words, sympathy and sociability. We part company with our promise if we are unlike other men. We must see to it that the means by which we wish to draw admiration be not absurd and odious. Our motto, as you know, is “Live according to Nature”; but it is quite contrary to nature to torture the body, to hate unlaboured elegance, to be dirty on purpose, to eat food that is not only plain, but disgusting and forbidding. 5. Just as it is a sign of luxury to seek out dainties, so it is madness to avoid that which is customary and can be purchased at no great price. Philosophy calls for plain living, but not for penance; and we may perfectly well be plain and neat at the same time. This is the mean of which I approve; our life should observe a happy medium between the ways of a sage and the ways of the world at large; all men should admire it, but they should understand it also.
(Hat tip to Sebastian Marshall.)