As the good of the body is health, so the good of the soul is knowledge, which is indeed a kind of health of soul, by which a likeness to God is attained.—From the writings of John of Damascus.
17 [17a] Ὡς δὲ σώματος ἀγαθὸν ὑγεία, οὕτως ψυχῆς ἀγαθὸν γνῶσις θεοῦ, ὑγεία τις οὖσα ψυχῆς, καθ' ἣν πρὸς θεὸν ὁμοίωσις γίνεται.