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.

4976. 'And ministered to him' means that factual knowledge was assigned to its own good. This is clear from the meaning of 'ministering' as serving by supplying what another has need of, in this case as being assigned to since the subject is natural good to which factual knowledge is to be assigned. 'Ministering' is also used to describe known facts, for in the Word a minister and a servant mean factual knowledge or natural truth because this is subservient to good as its lord. Factual knowledge stands in relation to delight present in the natural man - or what amounts to the same, natural truth stands in relation to its good - in exactly the same way as water does to bread, or drink to food. Water or drink enables bread or food to be dissolved, and once dissolved to be conveyed into the blood, from which it passes into all parts around the body and nourishes them. Without the water or drink the bread or food is not broken down into extremely small particles and carried around the body to fulfill its purpose.

[2] The same applies to factual knowledge in relation to delight, or truth in relation to good. That being so, good longs for and desires truth, and does so because of the purpose such truth can fulfill by ministering to it and serving it. Food and drink also correspond to these. No one in the next life is nourished by any natural food or natural drink, only by spiritual food and spiritual drink, spiritual food being good, and spiritual drink truth. This is why, when bread or food is mentioned in the Word, angels understand spiritual bread or food, which is the good of love and charity; and when water or drink is mentioned they understand spiritual water or drink, which is the truth of faith. From this one may see what the truth of faith without the good of charity is, and also what kind of nourishment the former without the latter is able to supply to the internal man; that is to say, it is like the nourishment supplied by water or drink alone without bread or food. It is well known that a person fed on water or drink alone wastes away and dies.