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.

8767. 'And keep My covenant' means thus leading a good life, and as a consequence being joined [to the Lord]. This is clear from the meaning of 'keeping the covenant' as leading a life in accordance with the commandments, thus a life governed by good, and so being joined to the Lord. The reason why 'keeping the covenant' means leading a life in accordance with the commandments, thus leading a good life, is that the stipulations of the covenant were all the things that had been commanded, which were called testimonies, judgements, laws, and statutes, in particular the Ten Commandments. All these were also called the covenant because it was established through them. The fact that keeping them is leading a life in accordance with them is evident from the meaning of 'keeping' in the Word. Many times it speaks of hearing the commandments and keeping them, and in those places 'hearing' means accepting them in faith, and 'keeping' accepting them in life, that is, leading a life in accordance with them. The reason why 'keeping the covenant' also means being joined [to the Lord] is that in an overall sense 'a covenant' means being joined together, 665, 666, 1023, 1038, 1864, 1996, 2003, 2021, 6804. It has this further meaning because a person who leads a life in accordance with the commandments is joined to the Lord. For the commandments teach about life and also impart life, thereby opening the way to heaven and opening one's eyes to see the Lord.