Комментарий к Берешит 1:15

והיו למאורות AND LET THEM BE FOR LIGHTS — They shall serve also this purpose, namely, to give light to the world.

והיו למאורות, they should provide light for the physical universe.

להאיר על הארץ, they should dispense their light at a time when it is beneficial for the inhabitants of the earth.

"And they shall be for luminaries, etc.:" It added that their light and radiance should reach the earth, since it was possible that they should show light in the heavens and do all of the acts that are mentioned, without their shining upon the earth (Nachmanides - Ramban).

AND THEY SHALL BE FOR LIGHTS IN THE FIRMAMENT OF THE HEAVEN TO GIVE LIGHT UPON THE EARTH. He added here that their light should reach the earth since it is possible for the light to be seen in the heavens and perform all mentioned functions without lighting upon the earth. Hence He said that it be for lights in the firmament of the heaven, directed toward the earth and shining upon it.

And they will be for luminaries: The meaning of the verse is to tell that God commanded the light of the luminaries to break through the heavens and also to illuminate the earth; the explanation [of which] is that the luminaries should illuminate the entire expanse of the heavens and that their lights should also reach down until the earth. Also, it means [to teach] that God set them up, such that the strength of their light is in the heavens, and from that light that spreads out in the heavens, the earth is illuminated; as the earth does not have the power to withstand the strength of the light of the luminaries. And that is why it is exact to say, "to the luminaries in the firmament of the skies," the explanation [of which] is that they illuminate there; and its stating, "to illuminate on the earth," the explanation [of which] is that from the clear light of the skies is the earth illuminated.

והיו, they should also serve as luminaries, i.e להאיר על הארץ, to provide illumination on earth. Prior to the fourth “day” the sun and moon had already been sources of light for the earth. Suspending these luminaries in the sky on the fourth ”day” only made them visible to creatures who possessed a sense of sight. Their light also had an effect on all of these creatures, each according to their physical constitution.

And they were etc., to shine upon the earth: Since it is possible that their radiance would be visible by having them suspended in the firmament and the radiance would be above, as with the light of a candle. For this reason, [the Torah] explains that [the luminaries were] "to shine upon the earth;" that the light would shine specifically upon the earth.

They serve another purpose, that they provide light. This is in addition to the purpose of, “Divide between the day and the night.”

ברקיע השמים להאיר על הארץ, ”in the sky of theheavens to disseminate light all over the earth.” One of the luminaries’ functions is similar to that of lanterns which are also always placed on high poles to better illuminate their surroundings. According to the plain meaning of the text, the sun and moon are necessary to illuminate earth, whereas the light created on the first “day,” is needed to illuminate the heavenly regions, seeing that on the second “day,” a partition had been erected between the former and the latter by the horizon/atmosphere. Alternately, when the Torah reported that on the first “day” light came into existence, i.e. ויהי אור, this was the “light” which enabled “life” to exist, whereas here we speak about the light provided by the sun and moon respectively. Although as yet this “light” was not needed as the creatures for which the sun and moon were to shine had not been created yet, there were grasses and fruit bearing trees which needed it in order for them not to wither and die. The fruit could not have ripened without the rays of the sun. We also know from Deuteronomy 33,14, that there are plants which cannot grow without moonlight. Furthermore, G-d had created some living creatures such as creeping things and birds on the fifth “day,” and the means for their survival had to exist before they came into existence.

ויהי כן, G’d’s directive was executed and became a permanent feature of natural law.

And it was so: The two luminaries were made by the word of God and were placed in front of Him. And still while they were not yet placed, then And God made, etc.: He arranged them so that they would rule in the midst of the world.

For the world. Rashi explains that the sun and moon are to provide light for living beings. Thus Rashi says לעולם, rather than על הארץ as the verse does — to indicate that the light is for the people of the earth, since the earth itself does not need light.

And according to [the] words of [the Sages] (Chagigah 12:), of blessed memory, that the luminaries are in the second firmament, the luminaries only break through the [first] sky and the second sky shines upon the earth. And what they, of blessed memory, stated (Yoma 28b), "A cloudy day is full of sun," is not a contradiction to our words; since, in any case, even if the place of the sun spreads the power of the sun to its sides, there is a difference between [that] and the place that the sun is fixed, where it is more powerful. And a cloudy day goes back and spreads the power of the sun that remains directed at the earth - according to what [the earth] can endure - and, because of the clouds, spreads it at the top of the skies, and that is [what is meant by] "it is full of sun."