Arcana Coelestia #738
738. He is called 'a son of six hundred years' here because, as shown already, 'son' means intellectual truth. He is not however referred to as a son in verse 11 below because there the subject is his temptation as regards things of the will.
Malachi 2:4
4
And ye shall know that I have sent this commandment unto you, that my covenant might be with Levi, saith the LORD of hosts.