A person who somehow has a blocked ability to spiritually elevate (often erroneously and clumsily translated to as “impure” or “unclean”) typically has to wash their body in water. But even after they have washed, they are not able to elevate until the sun sets.
This is specifically cited twice in the Torah:
The person who touches such shall be impure until evening and shall not eat of the sacred donations unless he has washed his body in water. When the sun sets, he shall be pure; and afterward he may eat of the sacred donations, for they are his food.
And
If anyone among you has been rendered impure by a nocturnal emission, he must leave the camp, and he must not reenter the camp. Toward evening he shall bathe in water, and when the sun sets he may reenter the camp.
Why does the setting of the sun matter?
The answer is, as always, in the text itself. The setting of the sun is a precondition for certain kinds of connections with the divine! Specifically, Avraham at the Covenant Between the Parts:
And it was as the sun was setting, a deep sleep fell upon Abram, and a great dark dread descended upon him.
… When the sun set and it was very dark, there appeared a smoking oven, and a flaming torch that passed between those pieces.
And then Jacob also has a revelation after the sun set:
[Jacob] came upon a certain place and stopped there for the night, for the sun had set. Taking one of the stones of that place, he put it under his head and lay down in that place.
Jacob then sees the ladder connecting heaven to earth, with the angels ascending and descending.
In both cases, the events after the sun sets are of pivotal importance: they set the conditions for the Jews forever more.
There is a parallel commandment with the Passover offering:
At the place where the ETERNAL your God will choose to establish the divine name, there alone shall you slaughter the passover sacrifice, in the evening, when the sun sets, the time of day when you departed from Egypt.
The Passover Offering is recreating and reconnecting to the Exodus, when the people left Egypt and connected to G-d – it is very much like the Covenants of both Avraham and Jacob in this regard.
Which then makes the answer to our question very straightforward: A person who wishes to spiritually elevate cannot do so until they have recreated the same base condition that Avraham and Jacob – and the Children of Israel in Egypt – experienced.
Similarly, the few other times the Torah uses this phrase, the meaning lines up. For example, the Torah tells us If you take your neighbor’s garment in pledge, you must return it before the sun sets; … And if they are needy, you shall not go to sleep in their pledge; you must return the pledge when the sun sets, that they may sleep in their cloth and bless you; and it will be to your merit before the ETERNAL your G-d.
Though these commandments are commonly understood as a commandment for us to be kind, we can now use the way the phrase is found elsewhere in the Torah to also understand that returning a needed garment before sleep to be as a way to facilitate (or at least not block) the spiritual elevation of other people! The connection to Jacob is especially pointed: sleeping as comfortably as possible enabled a revelation!
P.S. When the opposite occurs, the rising of the sun after Lot flees Sodom, it is the END of divine connection. As the sun rose upon the earth and Lot entered Zoar. Lot never talks with G-d again.
Creativejudaism.org