Arcana Coelestia # 2637
2637. 'When Isaac his son was born to him' means when the Lord's Rational was made Divine. This is clear from the meaning of 'being born' as being manifested, dealt with in 2584, 2621, 2629, and from the representation of 'Isaac' as the Divine Rational, dealt with in 2630. The latter is said 'to be born' to Abraham when it has been made Divine, as also in verse 3 above, 'Abraham called the name of his son born to him', see 2628.
Arcana Coelestia # 2630
2630. 'Isaac' means the Divine Rational. This is clear from what has been stated already about Abraham, Isaac, and Jacob in 1893, 2066, 2083, to the effect that 'Abraham' represents the Lord's Supreme Divine, 'Isaac' the Divine Rational, and 'Jacob' His Divine Natural, as will also be clear from what comes later on where Isaac is the subject.