Arcana Coelestia#4670
4670. 'A son of seventeen years' means His state. This is clear from the ages measured in years of people mentioned in the Word - spiritual realities and states are meant by them, as these are by all other numbers. For all numbers in the Word have spiritual realities and states as their meaning, see 575, 647, 648, 1988, 2075, 2252, 3252, 4264, 4495, as also do years, 487, 488, 493, 893.
[2] It does indeed seem as though numbers of years, or ages measured in years, mean nothing else than numbers of years. This is because these numbers more than any others have so to speak a more specific historical application. But these numbers too include spiritual realities and states within them, as is clear from the applications given at Genesis 5 and from what has been stated at Genesis 17:1 and Genesis 25:7 about Abraham's age and at Genesis 35:28 about Isaac's. The same is clear in addition from the fact that no historical detail exists anywhere in the Word which does not include within it something heavenly into which it is also changed when it passes from the thought of the reader to the angels present with him, and through those angels into heaven where the spiritual sense rises up out of every historical reference in the Word.
[3] But what is meant by Joseph's being seventeen years old may be seen from the meaning which this number has elsewhere, namely a beginning, in this case the beginning of the representation through Joseph. As to its meaning a beginning and that which is new, see 755, 853. What is more, this number includes within itself in a general way, and so to speak potentially, all the things that are represented by 'Joseph' - 'seven' meaning that which is holy and 'ten' remnants. For 'seven' when used in the Word adds holiness to any meaning, see 881, while 'ten' means remnants, 576, 1906, 2284. The remnants present in the Lord were Divine and His own, and by means of them He united the Human Essence to the Divine Essence, 1906.
Arcana Coelestia#84
84. Verses 2-3 And on the seventh day God finished His work which He had made, and rested on the seventh day from all His work which He had made. And God blessed the seventh day and made it holy, for on that day He rested from all His work which God had created when making it.
The celestial man is 'the seventh day'; and because throughout the six days it has been the Lord at work, that man is called 'His work'. In addition, because conflict at that point ceases, the Lord is said 'to rest from all His work'. It was for this reason that the seventh day was made holy and was called the Sabbath from a word for 'rest'; and it was in this manner that man was created, formed, and made, as may be seen plainly from the words themselves.