Children And Perfection

Κάκεῖνο, ὅπερ ἔφης, συνήγορον εὑρίσκω τῶν πρώην γραφέντων σοι, μὴ παιδία γίνεσθαι ταῖς φρεσὶν, ἀλλὰ τῇ κακίᾳ νηπιάζειν, ταῖς δὲ φρεσὶ τελειοῦσθαι, τοῦ πανσόφου γράψαντος Παύλου. Οὐ γὰρ ἔστιν, οὐκ ἔστι μὴ ἀποσμήξαντας τὴν κακίαν, καὶ νηπιάσαντας πρὸς ἀγνείαν, ἢ φρεσὶ τελειωθῆναι, ἢ εἰς ἄνδρα τέλειον εργάτην ἀνεπαίσχυντον ἀναβῆναι. Ἅγιος Ἰσίδωρος Του Πηλουσιώτου, Βιβλίον Πρῶτον, Ἐπιστολὴ ΥΜΒ', Ἰσιδωρῳ Διακονῳ Source: Migne 78.425b

That, which as you say, I set down among the things recently written to you, does not mean that we should be like children in our minds, but that we should be childlike in wickedness while perfecting the mind. Unless we are cleansed of all wickedness it is not possible that we shall regain a childlike purity and chastity, so that we might achieve perfection of mind and be lifted up to the blameless work of the perfect man. Saint Isidore of Pelusium, Book 1, Letter 442, To Isidore The Deacon