Sons Of Promise

Nos autem, fratres, secundum Isaac promissionis filii sumus. Apostolum et similes ei secundum Isaac promissionis esse filios, nulla intellgentiae difficultas est. Sed quia Origenes hunc locum edisserens, ita Apostoli posuit exemplum: 'Vos autem, fratres, secundum Isaac promissionis filii estis, quaeritur quomodo Galatas, quos stultos appellarat, et incoepisse dixerat spiritu, carne finire, nunc secundum Isaac filios repromissionis vocet? Dicimus itaque Apostolum ideo eos appellare secundum Isaac filios repromissionis, quia non penitus eorum desperet salutem, et rursum eos ad spiritum quo coeperant aestimet reversuros, fiantque filii liberae. Qui si carne fuerint consummati, filii sunt ancillae. Sanctus Hieronymus, Commentariorum in Epistolam ad Galatas, Liber II, Cap IV Source: Migne PL 26.392a-b

We are, brothers, the sons of the promise, as Isaac. 1 That the Apostle and those like him are the sons of promise as Isaac is not difficult to understand. But since Origen also writes on this passage concerning the Apostle, when he says, 'You are, brothers, the sons of the promise, as Isaac,' and asks how the Galatians, whom the Apostle has called foolish, and whom he has said have begun in the spirit to end in the flesh, are now sons of promise according to Isaac, we say that the Apostle calls them sons of promise according to Isaac because he has not utterly despaired of their salvation, and again that he judges that they have begun to turn back to the spirit, and to become sons of the free woman. Those who, if they had reached the end of the flesh, would have been sons of the slave girl. Saint Jerome, Commentary on the Letter to the Galatians, Book 2 Chap 4 1 Gal 4.28