Principal Doctrine 3
ὅρος τοῦ μεγέθους τῶν ἡδονῶν ἡ παντὸς τοῦ ἀλγοῦντος ὑπεξαίρεσις. ὅπου δʼἂν τὸ ἡδόμενον ἐνῇ, καθʼὃν ἂν χρόνον ᾖ, ουκ ἔστι τὸ ἀλγοῦν ἢ λυπούμενον ἢ τὸ συναμφότερον.
The limit of quantity in pleasures is the removal of all that is painful. Wherever pleasure is present, as long as it is there, there is neither pain of body nor of mind, nor of both at once.
Inwood and Gerson:
The removal of all feeling of pain is the limit of the magnitude of pleasures. Wherever a pleasurable feeling is present, for as long as it is present, there is neither a feeling of pain nor a feeling of distress, nor both together.
The limit of enjoyment is the removal of all pains. Wherever and for however long pleasure is present, there is neither bodily pain nor mental distress.
from Plato's Philebus:
καὶ ἄλλα γε δὴ μυρία ἐπιλείπω λέγων, οἷον μεθ᾽ ὑγιείας κάλλος καὶ ἰσχύν, καὶ ἐν ψυχαῖς αὖ πάμπολλα ἕτερα καὶ πάγκαλα. ὕβριν γάρ που καὶ σύμπασαν πάντων πονηρίαν αὕτη κατιδοῦσα ἡ θεός, ὦ καλὲ Φίληβε, πέρας οὔτε ἡδονῶν οὐδὲν οὔτε πλησμονῶν ἐνὸν ἐν αὐτοῖς, νόμον καὶ τάξιν πέρας ἔχοντ᾽ ἔθετο: καὶ σὺ μὲν ἀποκναῖσαι φῂς αὐτήν, ἐγὼ δὲ τοὐναντίον ἀποσῶσαι λέγω. σοὶ δέ, ὦ Πρώταρχε, πῶς φαίνεται;
Soc. I omit ten thousand other things, such as beauty and health and strength, and the many beauties and high perfections of the soul: O my beautiful Philebus, the goddess, methinks, seeing the universal wantonness and wickedness of all things, and that there was in them no limit to pleasures and self-indulgence, devised the limit of law and order, whereby, as you say, Philebus, she torments, or as I maintain, delivers the soul-What think you, Protarchus?
There are countless other things which I pass over, such as health, beauty, and strength of the body and the many glorious beauties of the soul. For this goddess,1 my fair Philebus, beholding the violence and universal wickedness which prevailed, since there was no limit of pleasures or of indulgence in them, established law and order, which contain a limit. You say she did harm; I say, on the contrary, she brought salvation. What do you think, Protarchus?