Arrian, Discourses of Epictetus
4.11.9-18 (tr. Robin Hard):
 We should endeavour as far as possible to achieve something similar with
regard to the body too. It is impossible that there should not be some flow of
mucus from a human being, since he is constituted in the way that he is. For that
reason, nature has created hands, and has made our nostrils themselves like tubes
to carry away the fluids. So if anyone sniffs them up again, I say that he isn't
acting as is appropriate for a human being.  It was impossible that our feet
should not get muddy, or dirty at all, when we pass through filth of that kind;
nature has thus provided us with water and with hands.  It was impossible
that some dirt should not get left behind on our teeth when we’ve eaten; and so
nature says to us, 'Clean your teeth.' Why? So that you may be a human being,
and not a wild beast or a pig.  It was impossible that through our sweat and
the rubbing of our clothes, some uncleanness should not be left behind on our body and need to be cleaned off; for this reason, we have water, oil, hands, a
towel, a scraper, and everything else that is used for cleaning the body.  Not
in your case? But a smith will remove the rust from his iron, and has tools made
for that purpose, and you yourself will wash your plate before you eat, unless
you're irredeemably dirty and unclean; and yet when it comes to your poor body,
you don't want to wash it and make it clean?
'Why should I?', the man says.
 I'll tell you again: in the first place, to act as is appropriate for a human
being, and secondly, so as not to disgust those whom you meet.  You're
doing something of that kind even here, without realizing it. You think that you
have the right to give out a bad smell. Very well, you may have it. But do you
think that those who sit by you, or recline by you at table, should have it too, and
those who kiss you?  Oh, go off into the desert somewhere, as you deserve,
and live there alone, taking pleasure in your own odours. But living in a city as
you do, what sort of a person do you think you're showing yourself to be, to
behave in such a thoughtless and inconsiderate manner?  If nature had
entrusted a horse to your care, would you have neglected it and failed to look
after it? Well then, think of your own body as a horse that has been entrusted to
you; wash it, wipe it, make it such that no one will turn away from you, no one
will seek to avoid you.  And who doesn't want to avoid a man who is dirty,
who smells, and whose skin looks even worse in colour than someone who has
been spattered with dung? In the latter case, the smell rises merely from the
outside and is accidental, but in the other, it arises from neglect, and thus comes
from within, as though from some form of putrefaction.
 Δεῖ δέ τι ἐοικὸς τούτῳ καὶ ἐπὶ σώματος φιλοτεχνεῖν
κατὰ τὸ ἐνδεχόμενον. ἀμήχανον ἦν μύξας μὴ ῥεῖν τοῦ ἀνθρώπου τοιοῦτον ἔχοντος τὸ σύγκραμα· διὰ τοῦτο χεῖρας ἐποίησεν ἡ φύσις καὶ αὐτὰς τὰς ῥῖνας ὡς σωλῆνας πρὸς τὸ ἐκδιδόναι τὰ ὑγρά. ἂν οὖν ἀναρροφῇ τις αὐτάς, λέγω ὅτι οὐ ποιεῖ ἔργον ἀνθρωπικόν.  ἀμήχανον ἦν μὴ πηλοῦσθαι τοὺς πόδας μηδὲ ὅλως μολύνεσθαι διὰ τοιούτων τινῶν πορευομένους· διὰ τοῦτο ὕδωρ παρεσκεύασεν, διὰ τοῦτο χεῖρας.  ἀμήχανον ἦν ἀπὸ τοῦ τρώγειν μὴ ῥυπαρόν τι προσμένειν τοῖς ὀδοῦσι· διὰ τοῦτο "πλῦνον," φησίν, "τοὺς ὀδόντας." διὰ τί; ἵν᾿ ἄνθρωπος ᾖς καὶ μὴ θηρίον μηδὲ συίδιον.  ἀμήχανον μὴ ἀπὸ τοῦ ἱδρῶτος καὶ τῆς κατὰ τὴν ἐσθῆτα συνοχῆς ὑπολείπεσθαί τι περὶ τὸ σῶμα ῥυπαρὸν καὶ δεόμενον ἀποκαθάρσεως· διὰ τοῦτο ὕδωρ, ἔλαιον, χεῖρες, ὀθόνιον, ξύστρα, νίτρον, ἔσθ᾿ ὅθ᾿ ἡ ἄλλη πᾶσα παρασκευὴ πρὸς τὸ καθῆραι αὐτό.  οὔ· ἀλλ᾿ ὁ μὲν χαλκεὺς ἐξιώσει τὸ σιδήριον καὶ ὄργανα πρὸς τοῦτο ἕξει κατεσκευασμένα, καὶ τὸ πινάκιον αὐτὸς σὺ πλυνεῖς, ὅταν μέλλῃς ἐσθίειν, ἐὰν μὴ ᾖς παντελῶς ἀκάθαρτος καὶ ῥυπαρός· τὸ σωμάτιον δ᾿ οὐ πλυνεῖς οὐδὲ καθαρὸν ποιήσεις;
—Διὰ τί; φησίν.—
 Πάλιν ἐρῶ σοι· πρῶτον μὲν ἵνα τὰ ἀνθρώπου ποιῇς, εἶτα ἵνα μὴ ἀνιᾷς τοὺς ἐντυγχάνοντας.
 τοιοῦτόν τι καὶ ἐνθάδε ποιεῖς καὶ οὐκ αἰσθάνῃ. σαυτὸν ἄξιον ἡγῇ τοῦ ὄζειν· ἔστω, ἴσθι ἄξιος. μή τι καὶ τοὺς παρακαθίζοντας, μή τι καὶ τοὺς συγκατακλινομένους, μή τι καὶ τοὺς καταφιλοῦντας;  ἔα ἄπελθ᾿ εἰς ἐρημίαν πού ποτε, ἧς ἄξιος εἶ, καὶ μόνος δίαγε κατόζων σεαυτοῦ. δίκαιον γάρ ἐστι τῆς σῆς ἀκαθαρσίας σὲ μόνον ἀπολαύειν. ἐν πόλει δ᾿ ὄντα οὕτως ἀπερισκέπτως καὶ ἀγνωμόνως ἀναστρέφεσθαι τίνος σοι φαίνεται;  εἰ δ᾿ ἵππον σοι πεπιστεύκει ἡ φύσις, περιεώρας αὐτὸν καὶ ἀτημέλητον; καὶ νῦν οἴου σου τὸ σῶμα ὡς ἵππον ἐγκεχειρίσθαι· πλῦνον αὐτό, ἀπόσμηξον, ποίησον, ἵνα σε μηδεὶς ἀποστρέφηται, μηδεὶς ἐκτρέπηται.  τίς δ᾿ οὐκ ἐκτρέπεται ῥυπαρὸν ἄνθρωπον, ὄζοντα, κακόχρουν μᾶλλον ἢ τὸν κεκοπρωμένον; ἐκείνη ἡ ὁσμὴ ἔξωθέν ἐστιν ἐπίθετος, ἡ δ᾿ ἐξ ἀθεραπευσίας ἔσωθεν καὶ οἱονεὶ διασεσηπότος.
W.A. Oldfather ad loc.:
The excesses, probably Oriental in origin, to which Christian ascetism soon went in regard to despising cleanliness, seem to have begun to manifest themselves already in the early second century among enthusiastic young Stoics and would-be Cynics. It is interesting to see how Epictetus, simple and austere as he was, vigorously maintained the validity of older Greek and Roman feeling in this regard.