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.

5962. 'And he sent his brothers away, and they went' means a concealment from view. This is clear from the meaning of 'sending away as removing them from himself, consequently his ceasing for that reason to be present with them any longer; and from the meaning of 'going' or going away as living, also living further away from, and abandoning too, dealt with in 3335, 3416, 3690, 4882, 5493, 5696, thus becoming concealed from view. The fact that a removal from the internal celestial and so a concealment of it is referred to now is clear from what follows in the internal sense.

[2] Anyone who does not know the nature of the state of life experienced by spirits and angels in heaven cannot know why a concealment of truth and good is referred to now, when immediately before this they had had the light of truth and good shining on them. The heavenly state is such that spirits and angels pass through morning, midday, and evening, also twilight and morning again, and so on. For them it is morning when the Lord is present, blessing them with evident happiness; and at this time they enjoy a perception of good. Midday has come when they dwell in the light of truths; and it is evening when they are removed from them, in which case the Lord seems to them to be more remote and to be concealed from them. All in heaven undergo and pass through these alternating states; without them they cannot be led to ever greater perfection. For those alternating states establish contrasts for them, and from those contrasts they gain more perfect perception, for from those contrasts they know what does not constitute happiness since they know from them what is not good and what is not true.

[3] It is astonishing, and rightly so, that one state never is or ever will be exactly like another, also that one spirit or angel does not pass through changes of state that are the same as those of another, for the reason that with respect to good and truth one spirit or angel is not exactly like another, even as no one person's face is identical to another's. Even so the Lord makes a unified whole out of those varying individuals. It is a general rule that every whole which has any specific character is made up of varying parts which are brought, as if through agreement and harmony with one another, into such a state of unanimity that they all present themselves as a unified whole. In heaven the unified whole which results or rather the process of being unified is effected by means of love and charity; see also 3241, 3267, 3744, 3745, 3986, 4005, 4149, 5598. In the Word the concealment meant by 'Joseph sent away his brothers, and they went' is called evening, which among the angels has come when they do not perceive that the Lord is present. For heaven possesses a constant perception of the Lord's presence; but when angels pass through a state in which they lack that perception they do not, as before, feel an affection for good or see truth. This causes them distress, but shortly after that, twilight comes, and so morning.