'Thirty' has a twofold significance because it is is the product of five and six, and also three and ten. From five multiplied by six, it signifies some aspect of combat, because 'five' signifies some part or aspect, and 'six,' combat. From three multiplied by ten, it signifies something full of remains of good and truth, because 'three' signifies fullness, and 'ten,' remains of good and truth. A composite number involves the same as the simple numbers it has as its factors.

(Referencias: 2 Samuel 5:4; Arcana Coelestia 5335; Luke 3, 3:23, 23; Numbers 4:3, 4:23, 4:30)

It's pretty easy for most people to read the Bible and get a sense for what “sheep” means without any help. They are simple, peaceful, trusting and willing to be led, and the image of the Lord as both a shepherd and a lamb reinforces a sense of innocence. And indeed, sheep represent people who desire what is good, to be good, and to do what is good. Arriving at such a state requires the work of a lifetime -- learning what's right, setting aside what's evil, determining to follow the Lord -- but once we arrive at such a state, we can be cared for by the Lord in peace.