37. As for the statement that 'the lights will be for signs, and for set times, and for days, and for years', this contains more arcana than can be presented at this point, though no arcanum at all is visible in the sense of the letter. For now only this can be said: Change in spiritual and celestial things takes place both on general and on particular scales, and is comparable to changes that take place through the day and through the year. Changes through the day are from morning to midday, from then on to evening, and through the night to the morning. Changes in the year similar, from spring to summer, from then on to autumn, and through winter to spring. These bring changes in temperature and amount of daylight, and so in the fertility of the earth. Compared to such changes are the changes that take place in spiritual and celestial things. Life without changes and variations would lead to sameness, and so no life at all. Good and truth would not be recognized and identified, let alone perceived. In the Prophets such changes are called 'ordinances', as in Jeremiah,

[Thus] said Jehovah who gives the sun for light by day and the ordinances of the moon and of the stars for light by night, These ordinances will not depart from before Me. Jeremiah 31:35-36.

And in the same prophet,

Thus said Jehovah, If I have not established My covenant of day and night, the ordinances of heaven and earth . . . Jeremiah 33:25.

But these things will in the Lord's Divine mercy be dealt with at Genesis 8:12.

7284. 'And Moses was a son of eighty years' means the state and essential nature of the law from God. This is clear from the representation of 'Moses' as the law from God, dealt with in 6771, 6827; and from the meaning of 'eighty years as the state and essential nature of the law from God, that is to say, among those who belonged to the spiritual Church, at the first time of visitation. What is meant specifically by 'eighty' cannot be stated because it entails the entire state and nature of the law from God among them at that time. 'Eighty' can mean a state of temptations, see 1963, and when it does so it entails the same meaning as forty. But because it is also the product of ten multiplied by eight, the meaning of eighty must be sought from these numbers as well. For what is meant by ten, see 576, 1906, 1988, 2284, 3107, 4638; and for what is meant by eight, 2044, 2866. In general all numbers serve to mean spiritual realities, and more particularly the states and essential nature of those realities, see 482, 487, 575, 647, 648, 755, 813, 1963, 1988, 2075, 2252, 3252, 4264, 4495, 4670, 5265, 5191, 5335, 5708, 6175.