Here, part way through Day One, God took a significant step in making the as yet uninhabitable earth habitable. He created light. What is light? At its most basic level, light is energy (see The Basics of Light, offsite). Light is a means of transferring energy through space. We can also say that light is electromagnetic radiation. Typically, when we use the word light, we think only of optical light. But optical light is only the portion of the complete spectrum of electromagnetic radiation that is visible to the human eye. In addition to optical light, for example, there exist gamma-rays, X-rays, ultraviolet, infrared, and radio waves. To illustrate the notion that light is energy, it is helpful to understand that light travels in waves of particles. Each particle is called a photon. Different kinds of photons carry different amounts of energy. An X-ray photon, for example, carries much more energy than an optical or radio photon. These photons travel in waves, or measurable speeds of vibration. In the optical realm, “blue light has a higher frequency of vibration (or a shorter wavelength) than … red light.” Light, like most entities in the created order, is a lot more complicated that it appears to be.

It is significant to note that God created light on Day One before He created the sun or moon or any stars. That did not take place until the fourth day. There are some who object to the idea that God would be recorded as creating light before the existence of the sun. But that is a specious objection. Let me illustrate by asking a couple of simple questions: Has man been able to create artificial light independent of the sun? The answer is, “Of course!” We burned wood or anything flammable as an artificial light source for millennia. More recently we burned coal oil or kerosene as a light source in our lamps. Then we created the incandescent light bulb. We have invented fluorescent lights and neon lights. More recently, man has invented LED lights (Light-Emitting Diodes). If man can create artificial light sources that operate without the sun, why could God not create light on Day One that existed independently of the yet-to-be-created sun or stars? That is a trifling matter for God. What would be the source of the light that God created on Day One? That source would be God Himself. Let me illustrate this way. The ultimate capital city of New Earth will be New Jerusalem, described in significant detail in Revelation 21:1-22:15. We are told, “And the city has no need of the sun or of the moon to shine on it, for the glory of God has illumined it, and its lamp is the Lamb. The nations will walk by its light, and the kings of the earth will bring their glory into it. In the daytime (for there will be no night there) its gates will never be closed;” (Rev. 21:23-25). “God is light” (1 John 1:5), both in a physical and a metaphysical sense. The light that God spoke into existence consisted, at least, of a visible (optical) and probably an invisible display of His own glory. And this transference of energy from God to the physical universe would have taken place irrespective of the sun or any stars. There was an independent light source created on Day One in relationship to which the planet earth rotated to complete the first cycle of Day One (Gen. 1:5). That light source, I submit, was a visible manifestation of the glory of God.

God saw that the light was good (Gen. 1:4a). This almost amounts to a Divine pun. When the light appeared, God could see (raah) that it was good (insert smiley face). The light, of course, did not enable God to see. He sees equally well in darkness or light (Psa. 139:11-12, demonstrated by Psa. 139:13-16). But man cannot see at all in total darkness, and God was incrementally molding the earth and the universe into conditions that were optimal for man to thrive and enjoy. (See The Privileged Planet.) Good (tob) means that God perceived the light as being good, pleasant, or agreeable. If there were no (optical) light, think of the incredible joys we would be denied! A blind person can experience a great deal of life. He still possesses intelligence and can communicate. But think of all the incredible vistas he would never experience! We could also add that light, as being good (tob), is beneficial. Light, for example, provides warmth for the planet, absolutely necessary for survival in the frigid realms of space, and it provides a necessary engine for photosynthesis. Photosynthesis is the ability God has given plants to produce complex organic materials, especially carbohydrates, from water, carbon dioxide, and inorganic salts, using light as a source of energy along with the aid of chlorophyll and associated pigments. So light is beneficial to plants, and since plants would be the food source for both animals and man (Gen. 1:29-30), light would also be good, in the sense of beneficial, to man and animals on that account.

Henry M. Morris (The Genesis Record, pp.56-57) speculates in a remarkable way on the action of the Godhead in creation to this point:

All the types of force and energy which interact in the universe involve only electromagnetic, gravitational, and nuclear forces; and all of these had now been activated. Though no doubt oversimplified, this tremendous creative act of the godhead might be summarized by saying that the nuclear forces maintaining the integrity of matter were activated by the Father when He created the elements of the space-mass-time continuum, the gravitational forces were activated by the Spirit when He brought form and motion to the initially static and formless matter, and the electromagnetic forces were activated by the Word when He called light into existence out of the darkness. Of course, God is One, and all three persons of the Godhead actually participated in all parts of the creation and continue to function in the maintenance of the universe so created.

and God separated the light from the darkness (Gen. 1:4b). When Moses wrote these words, he could not possibly have known about the portions of electromagnetic radiation that are invisible to the human eye. His concern (and God’s concern also) was differentiating between optical light and darkness. Some observations about light are in order here.

Light as initially pervasive. First, when God initially created light, it appears that light may have been pervasive. What do I mean by pervasive? Let me illustrate. In the distant future, God will create New Heaven(s) ("heavens" - in the OT the noun shâmayim appears only in the plural, and in the NT the Greek noun ouranos appears both in the singular and in the plural). The respective nouns for "heaven(s)" are plural in Isa. 65:17; 66:22; 2 Pet. 3:13, and singular in Rev. 21:1). He will also create New Earth (Isa. 65:17; 66:22; 2 Pet. 3:13; Rev. 21:1) because the existing heaven (universe) and earth have been irremediably contaminated by sin, decay, and death.

From an exceedingly high mountain, John was privileged to see the Holy City, New Jerusalem in the process of descending to or near New Earth (Rev. 21:2, 10) from the Heaven where God presently dwells. This New Jerusalem John saw was continually manifesting the glory of God in terms of an optical brilliance (Rev. 21:11). The glory of God and the Lamb (Jesus) illuminating the city was so intense that there was no need of either sun or moon to shine on it (Rev. 21:23). This brilliant glory John saw was not confined only to the city. He predicted that when these conditions manifest themselves in the future, the nations of New Earth will be able to function by means of the city’s great light, and the kings of New Earth will be able to transport their glory (presumably produce and manufactured goods) into the city twenty four hours a day. This will be true because there will never be any night there and the gates of the city will never be closed (Rev. 21:24-26). So the optically unveiled glory of God and the Lamb will be so great that there will be a visible brilliance both within the city and an external brilliance from the city casting light on huge portions of New Earth. (It is likely, in view of the present participle descending (katabaino) used in both Rev. 21:2 and 10, that the enormous city never actually rests upon New Earth, but rather is suspended as a satellite city, perhaps in geosynchronous orbit above the land of Israel on New Earth.) Not only will there be an external brilliance from the glory of God and of the Lamb emanating from New Jerusalem, but there will be an internal brilliance. Apparently there will be no need of artificial lighting within the buildings and homes of the city. John affirms that there will be no need, not only of illumination from the sun, nor either for any illumination from any lamp (Rev. 22:5). So the glory of God and of Jesus will not only illumine the city and radiate outward from the city, but it will illuminate the interiors of buildings and rooms in the city! This light from the glory of God will be pervasive indeed.

I say all that to say this: Evidently when God said, “Let there be light!” on Day One (Gen. 1:3), that light was pervasive in the sense that it illuminated the whole hemisphere of the earth facing that light. At the same time, God knew that the finite creatures He would create would need periodic, regular rest. For that, there must be a regular period of darkness. So part of God’s creative act with reference to light on Day One was not to obliterate darkness entirely, but to allow for alternating periods of light and darkness as the Earth rotated on its axis in reference to that light He had created on Day One (Gen. 1:3). So God centralized or focused the light reflecting his own innate glory to allow for nocturnal rest and rejuvenation. It is in that sense, I believe, that God separated the light from the darkness.

Light as functionally good. Second, some, unfortunately, have portrayed light upon the newly created earth as being good (tob) not only in an aesthetic and functional sense, but in a moral, ethical sense. And the darkness, they opine, signifies an unethical, unholy, evil aura (Ross, TBKC, I, pp. 28-29). In that sense, they hypothesize, the initial earth must have become contaminated. And by whom? By Satan, of course. Now it is true, of course, that later on in time and in Scripture, light and darkness are portrayed as polar opposites in the moral, ethical spectrum (see e.g. Isa. 5:20; 9:2; Matt. 6:23; John 3:19-21; 8:12; 12:46; Rom. 13:12; 2 Cor. 6:14; Eph. 5:8; 1 Thess. 5:5; 1 Pet. 2:9; 1 John 1:5; 2:9). And that is the point. The negative ethical and moral connotation of darkness was a later development. The difficulty with the “darkness is evil” hypothesis in Genesis 1:2-5 is that there is NO RECORD in the text of Gen. 1-2 that Satan was present on Earth any time before his mention in Gen. 3. In fact, there WAS NO SIN in connection with the Earth God created. So the darkness that needed to be rectified by light was not an ethical or moral darkness, but a functional and aesthetic deficiency. If it is dark, neither man, nor animal can see, and plants, the source of food for both, cannot grow. So created life could not survive without light. To insist that the darkness of Genesis 1:2-5 signified an ethical or moral deficiency is to import later ideas from later passages of Scripture into a beginning text in which they do not exist. Quite to the contrary, periodic darkness was necessary to provide nightly rest for the creatures God would soon create. And the darkness would never be total, for God would create a lesser light, the moon, to govern the nighttime (Gen. 1:16). Furthermore, God would later pronounce the developments upon earth, which included alternating periods of light and darkness as being good (tob) (Gen. 1:16-18).

God called the light day, and the darkness He called night (Gen. 1:5a). This is the first of five times that God “called” in this Creation passage (Gen. 1:1-2:3). Each time (in this context) the verb called (qara) means that God named or labeled an entity. (1) God called the light day (Gen. 1:5). (2) God called the darkness night (Gen. 1:5). (3) God called the expanse heaven (Gen. 1:8). (4) God called the dry land earth (Gen. 1:10). (5) God called the gathered waters seas (Gen. 1:10). ***

In Hebrew thought, the idea of naming something is not merely attaching a random label to it. It carries the idea of identifying the essence of that thing (see H. C. Leupold, Exposition of Genesis, I, p. 55, i.e. Section 1.55). The idea of naming something or labeling it also shows a certain mastery of that entity. (See Constable, Notes on Genesis, see comments on Gen. 1:5). See Genesis 41:45; 2 Kings 24:17; Daniel 1:7.) To name or identify or classify something is part of the very nature of God. Since God later created man in His own image and likeness (Gen. 1:26-27), He would bring animals to man and see what man would call (qara) them. And whatever man called (qara) a living creature, that was its name (shem) (Gen. 2:19). Genesis 2:20 records, literally, that the man “called (qara) names (shem)” to all the cattle, birds and beasts. That naming/labeling/classifying process revealed to man experientially that he had no suitable helper, as did the animals. After God created a female counterpart to man and brought her to him, the man called (qara) her woman (Gen. 2:23). The point is this: to call something is to name it, or accurately classify it and, to a certain degree, to exercise mastery over it. By way of illustration, we have all gone to the doctor with certain symptoms that we cannot identify. When he diagnoses our illness, we are somehow comforted. We don’t feel any better physically, but we feel better emotionally and psychologically, because both the doctor and we ourselves now have a degree of mastery over the inexplicable symptoms. We have the flu, or the ankle is badly sprained but not broken. Even if we are diagnosed with some kind of cancer, there is a certain amount of relief in knowing what kind of cancer we have and what the alternative methods of treatment are and what our prognosis might be. Similarly, those who favor abortion seek to control others’ perception of them by naming themselves as “pro-choice” rather than “those who seek to kill unborn babies.” God exercised mastery over the conditions of light and darkness by classifying the light as "day" and the darkness as "night."

These two labels are very geocentric and anthropocentric. By geocentric I mean that day and night have significance with respect to our earth. The existence of day and night demonstrates that the light that was initially pervasive was now localized, and that the earth was now regularly rotating in respect to the light source God had just created. Out in the middle of deep space, the terms day and night have no significance. Their significance is related to the earth. By anthropocentric, I mean that the terms day and night have primary significance for man, as opposed to animals. Obviously animals can differentiate between light and darkness, but they don’t call the darkness "night" nor do they call the light "day." Those are human terms, understood by man. God labeled the darkness and the light for man’s benefit, not for the benefit of animals.

What is the meaning of the word day (yom)? Here it clearly means the illuminated portion of a 24-hour period of time. So also night (layelah) refers to the non-illuminated portion of a 24-hour day. So in the very first occurrence of the word day in the Bible, it is self limiting. It is unequivocally linked to a 24-hour period of time, not a vast span of time (as theistic evolutionists would have us believe).