Letter 236: When your own strength fails — as it will — calling on God is not weakness.

To Heronius. Why the Lord did not make the stones into loaves. The stones were not turned into loaves by Christ, most excellent one, not because the hour for miracles was not yet present, as the perversely idle declaim, but because the request was a vain one, and fitting to the one who made it [the devil, who tempted Christ in the wilderness: Matthew 4:3]. For God bestows all things by weight, and by measure, and by need. But where the thing sought is superfluous, to work a miracle is altogether untimely.

Διὰ τί τοὺς λίθους οὐκ ἐποίησεν ἄρτους ὁ Κύριος. Οἱ λίθοι, ἄρτοι παρὰ Χριστοῦ οὐ γεγόνασιν, ἄριστε, οὐχὶ τῆς ὥρας τῶν θαυμάτων [ἔτι] μὴ παρούσης, ὡς οἱ καχόσχολοι ῥητορεύουσιν, ἀλλὰ τῆς αἰτήσεως ματαίας οὔσης, καὶ τῷ ζητοῦντι πρεπούσης. Θεὸς γὰρ πάντα στάθμῃ (75), καὶ μέτρῳ, καὶ χρείᾳ χαρίζεται. Ἔνθα δὲ [τὸ] περιττὸν τὸ ζητούμενον, καὶ τὸ θαυματουργεῖν πάντως οὐκ εὔκαιρον.