Arcana Coelestia # 6171
6171. 'And they had a possession in it' means given and set in order thus by the internal. This is clear from the meaning of 'a possession' as the position spiritual life occupies, dealt with in 6103; and since Joseph was the one who gave them that possession, verse 11, the giving and setting in order of that position by the internal is meant. It follows from the whole train of thought that this is what is meant.
Thirty
'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.
(Odkazy: 2 Samuel 5:4; Arcana Coelestia 5335; Luke 3, 3:23, 23; Numbers 4:3, 4:23, 4:30)