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.

1023. That 'and I, behold I am establishing My covenant' means the Lord's presence in charity becomes clear from the meaning of 'a covenant', dealt with in 666, where it was shown that 'a covenant' means regeneration, and in particular the conjunction of the Lord with a regenerate person by means of love. It was also shown there that the heavenly marriage is the actual covenant itself, and that consequently the heavenly marriage exists with every regenerate person. The nature of this marriage or covenant has also been shown already.

[2] The heavenly marriage with the member of the Most Ancient Church existed in the area of his own will, but the heavenly marriage with the member of the Ancient Church came into existence in the area of his own understanding. Actually when the will part of man's mind had become utterly corrupted, the Lord in miraculous fashion separated the area of his own understanding from that corrupted will part, and within the area of man's own understanding He formed a new will, which is conscience. Into conscience He infused charity, and into charity innocence, and in this manner joined Himself to man, or what amounts to the same, established a covenant with him.

[3] To the extent that the area of a person's own will can be separated from this understanding part the Lord is able to be present with him, that is, to join Himself or establish a covenant with him. Temptations and similar means of regeneration render inactive the area of a person's own will, so that it is reduced to nothing and so to speak dies. To the extent that this happens the Lord can operate within charity by means of conscience implanted in the area of a person's own understanding. This is what is called 'a covenant' here.