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.

487. 'Days means periods of time and states in general. This has been shown in Chapter 1, where the 'days of creation' have no other meaning. In the Word it is very common for a whole period of time to be called 'a day', as it clearly is in the present verse and in verses 5, 8, 11, 14, 17, 20, 23, 27, 31, below; and therefore the states that belong to periods of time in general are meant by 'days' as well. And when 'years' is attached, then periods of years mean the natures of those states, and so the states in particular.

[2] The most ancient people had their own particular numbers which they would use to mean different aspects of the Church - for instance, the numbers three, seven, ten, twelve, and many which they obtained from these and other numbers - and in so doing incorporated states of the Church. These numbers therefore contain arcana that would require considerable effort to unravel. Really a number was an evaluation of the states of the Church. The same feature occurs throughout the Word, especially in the prophetical. And the religious ceremonies of the Jewish Church also entail numbers specifying periods of time as well as quantities; for example, in connection with sacrifices, minchahs, oblations, and other practices, which in every case have special reference to holy things. Consequently eight hundred in this verse, nine hundred and thirty in the next, and the numbers of years mentioned in the verses that follow after that, embody in particular more matters than can possibly be retold; matters, that is to say, which have to do with changes in the state of their Church in relationship to their own general state. Later on, in the Lord's Divine mercy, the meaning of the simple numbers up to twelve will be given, for without knowing these first of all no one can grasp what compound numbers mean.