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.

5658. 'Our silver in its full weight' means truths commensurate with each one's state. This is clear from the meaning of 'silver' as truth, dealt with in 1551, 2954; and from the meaning of 'weight' as the state of something as regards good, dealt with in 3104, so that truths commensurate with each one's state means commensurate with the good they are able to receive. Many places in the Word make reference to weights or to measures, but no weight nor any measure is meant in the internal sense. Rather states so far as the good involved in some reality is concerned are meant by 'weights', while states so far as the truth involved in it is concerned are meant by 'measures'. The same applies to the properties of gravity and spatial magnitude; gravity in the natural world corresponds to good in the spiritual world, and spatial magnitude to truth. The reason for this is that in heaven, where correspondences originate, neither the property of gravity nor that of spatial magnitude exists because space has no existence there. Objects possessing these properties do, it is true, seem to exist among spirits, but those objects are appearances that have their origins in the states of goodness and truth in the heaven above those spirits.

[2] It was very well known in ancient times that 'silver' meant truth; therefore the ancients divided up periods of time ranging from the earliest to the latest world epochs into the golden ages, the silver ones, the copper ones, and the iron ones, to which they also added the clay ones. They applied the expression 'golden ages' to those periods when innocence and perfection existed, when everyone was moved by good to do what was good and by righteousness to do what was right. They used 'silver ages' however to describe those times when innocence did not exist any longer, though there was still some sort of perfection, which did not consist in being moved by good to do what was good but in being moved by truth to do what was true. 'Copper ages' and 'iron ages' were the names they gave to the times that were even more inferior than the silver ones.

[3] What led those people to give periods of time these names was not comparison but correspondence. For the ancients knew that 'silver' corresponded to truth and 'gold' to good; they knew this from being in communication with spirits and angels. For when a discussion takes place in a higher heaven about what is good, this reveals itself among those underneath them in the first or lowest heaven as what is golden; and when a discussion takes place about what is true this reveals itself there as what is silvery. Sometimes not only the walls of the rooms where they live are gleaming with gold and silver but also the very air within them. Also, in the homes of those angels belonging to the first or lowest heaven who are moved by good to live among what is good, tables made of gold, lampstands made of gold, and many other objects are seen; but in the homes of those who are moved by truth to live among what is true, similar objects made of silver are seen. But who at the present day knows that correspondence was what led the ancients to call ages golden ones and silver ones? Indeed who at the present day knows anything at all about correspondence? Anyone who does not know this about the ancients, and more so anyone who thinks pleasure and wisdom lie in contesting whether such an idea is true or untrue, cannot begin to know the countless facets there are to correspondence.