Ὧν ἡ σοφία παρασκευάζεται εἰς τὴν τοῦ ὅλου βίου μακαριότητα, πολὺ μέγιστόν ἐστιν ἡ τῆς φιλίας κτῆσις.
Of all the means wisdom procures sublime happiness throughout the entirety of one's life, the most important by far is the acquisition of friends.
Diogenes Laertius, Vitae Philosophorum, X.1.148 [27]. My translation.