'Three years old,' as in Genesis 15:9, implies all the times and states of the church, which appears from the meaning of 'three' in the Word, a full time of the church from its origin to its end, and as a result, every state of it. So, 'the third day' signifies the end state of the church. 'The third week,' 'the third month,' 'the third year, and 'the third age' signify the same thing. Because the number three signifies the state of the church, it also signifies the state of every individual who is and everything that is a church.

(Referencat: Arcana Coelestia 1825)