“Suffering becomes beautiful when anyone bears great calamities with cheerfulness, not through insensibility but through greatness of mind.”

Widely attributed since the mid to late 19th century, this apparently derives from a gloss or commentary on the following passage from Aristotle's Nicomachean Ethics (c. 325 BC), Book 1, Ch. XI (Bekker No. 1100b.13–14):
ὅμως δὲ καὶ ἐν τούτοις διαλάμπει τὸ καλόν, ἐπειδὰν φέρῃ τις εὐκόλως πολλὰς καὶ μεγάλας ἀτυχίας, μὴ δι᾽ ἀναλγησίαν, ἀλλὰ γεννάδας ὢν καὶ μεγαλόψυχος. εἰ δ᾽ εἰσὶν αἱ ἐνέργειαι κύριαι τῆς ζωῆς, καθάπερ εἴπομεν, οὐδεὶς ἂν γένοιτο τῶν μακαρίων ἄθλιος
But nevertheless, even in these [misfortunes], nobility of the soul is conspicuous, when a man bears and digests many and great misfortunes, not from insensibility, but because he is high spirited and magnanimous. But if the energies are the things that constitute the bliss or the misery of life, as we said, no happy man can ever become miserable.
A New Translation of the Nicomachean Ethics of Aristotle (1835), 3rd. ed., Oxford: J. Vincent. p. 30
Nevertheless even under these [misfortunes] the force of nobility shines out, when a man bears calmly many great disasters, not from insensibility, but because he is generous and of a great soul. Setting happiness then, as we do, not in the outward surroundings of man, but in his inward state, we may fairly say that no one who has attained to the bliss of virtue will ever justly become an object of pity or contempt.
St. George William Joseph Stock, Lectures in the Lyceum or Aristotle's ethics for English readers (1897), p. 47
Misattributed