And G‑d said: “Let there be light.” And there was light. And G‑d saw the light, that it was good; and G‑d separated between the light and between the darkness. And G‑d called the light day, and the darkness He called night. And there was evening and there was morning, one day. (Genesis 1:3-5)
This short passage from Genesis presents several difficulties that many classical commentators struggle to address. The first problem has to do with darkness and the separation of light from darkness. As we know today, darkness is not a substance—it is merely the absence of light. The verse states that G‑d separated between the light and the darkness. Presumably, before this “separation,” the light and the darkness existed together. How is this possible? By definition, the presence of light means no darkness. How could light and darkness coexist, when darkness is nothing but the absence of light?
Furthermore, what does the separation between the light and the darkness mean? Is it a separation in space or in time? Does it mean, perhaps, that the light and the darkness coexist simultaneously, but in different places, that is, there are areas of space that are dark and other areas that are light? Or, does it mean that there was light at one moment, and darkness at another, as the next verse seems to suggest?
Another significant difficulty relates to the verse, “And there was evening and there was morning.” As we know, the diurnal (daily) cycle of morning and evening (or day and night) is due to the rotation of the earth around its axis. On the half of the planet facing the sun and illuminated by the sun’s light, it is day, whereas on the opposite side, which is in the shadow, it is night. This cycle is also affected by the orbital movement of the earth around the sun.
From the standpoint of Biblical cosmogony, however, the earth and the sun were not created yet. What meaning could the words “morning” and “evening” possibly have before the sun and the earth came into existence?
Last, the verse says:
And there was evening and there was morning, one day.” (Genesis, 1:5)
Why is the first day called yom ahad, i.e., “one day,” using a cardinal number, one, whereas all subsequent days are called the second day, the third day, etc., using ordinal numbers?
It seems that the latter difficulties may point the way to the resolution of the first difficulty. Let us start with the problem of morning and evening in the absence of the sun and the earth.
If we accept that this diurnal cycle predates the creation of the sun and the earth, this excludes our daily 24-hour cycle due to the rotation of the earth around its axis. We can also safely exclude any notion that the primordial cycle was a 24-hour cycle comprising twelve hours of darkness and twelve hours of light, both unrelated to any planetary motion. Many satellites and, indeed, human astronauts and cosmonauts have been in the past and are presently in space, and they did not observe any such cycle—it is total darkness in space. If it wasn’t a cycle of night and day, darkness and light, what could it be? At least on the allegorical level, I suggest that this cycle refers to the cycle of time.
Ancient Greek philosophers already noted that time is cyclical. This observation was not unique to Greeks—most ancient cultures measured time in agricultural cycles or by the daily cycle of day and night. Jews added the linear aspect of time—the notion of forward movement notion, the notion of progress. This is also not surprising. The Jewish scriptures speak of the creation of the world in the beginning and of messianic redemption at the end. When you have pinpointed the beginning and the end of time, what necessarily follows is that the world’s evolution from that beginning toward that end. Thus, in his book The Gifts of the Jews: How a Tribe of Desert Nomads Changed the Way Everyone Thinks and Feels (1999), Thomas Cahill suggests that Jews invented the forward progression of time. However, it would be a mistake to think that ancient Jews believed that time was only linear. Jews added the notion of progress to the cyclical conception of time, but did not replace it. The Jewish conception of time is like a spiral, with both cyclical and forward-moving elements.
Moreover, Jewish mysticism laid a theoretical foundation for the cyclical aspect of time, based on Ezekiel’s prophesy, Maaseh Merkavah. In his prophecy, Ezekiel speaks of four living creatures—four angelic beings—who are said to be running and returning (ratzo vashov). Kabbalah and Chasidut explained that this cycle of running and returning is what sets off the flow of time—the never-ceasing time-flux.
The cycle of ratzo vashov (running and returning) is creation’s response to a similar cycle mati velo mati (touching and not touching) that comes from the Creator. A single cycle of ratzo vashov constitutes an indivisible elemental cycle of time—a quantum of time, a chronon. It seems plausible that the Biblical reference to the cycle of “and there was evening and there is morning, one day” may allude to this elemental cycle of time, ratzo vashov. As the sages tell us, the Torah speaks in the language of man. The single cycle of evening and morning appears to be the most natural metaphor for the cycle of ratzo vashov.
This allegorical interpretation also resolves the question of the use of a cardinal number—one day. According to our allegorical interpretation, the Torah does not discuss here the sequence of days; instead, it defines the quantum of time—one chronon.
If we accept the above interpretation, it points to resolving the first difficulty—that of G‑d separating the light from the darkness.
As I explained in detail in my essay, “On the Nature of Time and the Age of the Universe,” time arises when we attempt to construe the meaning of a self-referential statement. Let us consider a sentence, “This statement is false.” If this statement is true, then it is, indeed, false. However, if it is false, then, to the contrary, it is true. In short, if it’s true, it’s false; and if it’s false, it’s true. So long as we don’t think about it, we can write such a sentence on a piece of paper and put it on the table or in a drawer—and nothing will happen. However, if we start thinking about it, struggling to construe its meaning, we set off an endless sequence: if it’s true, it’s false; and if it’s false, it’s true, but if it’s true, it’s false; but if it’s false, it’s true, etc., etc., etc. This is the beginning of the time-flux—the flow of time.
This is precisely how Kabbalists explained the origin of time, tracing its roots to the self-contradictory construct of mati velo mati—touching and not touching. Note that this “movement” of touching and not touching comes from the ultimate self-referential construct—G‑d. This initiative from the Creator elicits a reciprocal movement from the creations—ratzo vashov—running and returning. It is also a self-referential statement. Here is why.
Consider a godly soul—nefesh Elokit. When in a human body, it yearns for its Creator. The soul experiences a suicidal tendency to leave the body and to soar on high to merge with its Maker. In Jewish mysticism, it is called klot hanefesh—the expiration of the soul in ecstasy. This is the first phase of the movement—ratzo (running). Once elevated, the soul gets inspired with the original purpose and realizes that its place is down below, in the body, where it can do mitzvot (G‑d’s precepts) and transform the world to make it a dwelling place for G‑d. Having realized that, the soul recoils and returns to the body, only to feel once again the yearning to reunite with its source. This never-ending cycle of the soul running to and fro reflects the universal cycle of time—ratzo vashov. What is interesting to us in this metaphor is that as soon as the soul runs, it must return; and as soon as it returns, it must run—very similar to our self-referential statement, which is, as soon as it is true, it is false, and as soon as it is false, it is true.
Returning to the light and the darkness, we first notice that the light and the darkness are two opposites. In fact, it is the most striking pair of two opposites, emblematic of the dichotomy of true and false or a thesis and its antithesis—is there a better metaphor for these abstract concepts?
With this understanding, we can say that, perhaps, the coexistence of light and darkness before their separation by G‑d is the metaphor of a self-contradictory and self-referential statement. It is self-contradictory because the darkness is the opposite of the light, and the light is the negation of darkness. It is self-referential because darkness is nothing but the absence of light. Thus, before being separated, light and darkness are parallel to truth and falseness in the sentence, “this statement is false.” As we attempt to construe the meaning of this statement, we must separate its two opposite meanings in time: first, if it’s true, then it’s false; then if it’s false, it is true. This is, perhaps, the meaning of G‑d’s separation “between the light and between the darkness.”
Now, it all fits together. First, G‑d presents us with a self-contradictory and self-referential construct of light and darkness mixed together (although this state is only implied). Then, in the absence of man, who can construe the meaning of such a construct, G‑d does it for us and teases apart the light from the darkness, thereby setting off the flow of time—the time-flux. The next verse summarizes the result—“And there was evening and there was morning, one day”—and there we have the first half of the cycle and the second half of the cycle—one cycle of time in total, one quantum of time, one chronon.
 As is well known, Rabbi Shlomo Yitzchaki (Rashi) explains this inconsistency on a literal level by saying that at the end of the first day, there were no other days yet allow us to call it the first.
 It is explained at length in the series of discourses called Samach Vav by the fifth Rebbe of Chabad-Lubavitch, Rabbi Dovber—the Rebbe Rashab.
 The chronon, a quantum of time, was first introduced by Robert Lévi in 1927. See Robert Lévi (1927). “Théorie de l’action universelle et discontinue,” Journal de Physique et le Radium, 8 (4): 182–198. A quantum theory, in which time is a discrete variable, was proposed twenty years later by the Chinese theoretical physicist and Nobel Laureate Chen Ning Yang (also known as Yang Zhenning) in 1947. See C. N. Yang (1947), “On quantized space-time,” Physical Review, 72 (9): 874. A further development is found in the work of Piero Caldirola in 1980. See P. Caldirola, (1980) “The introduction of the chronon in the electron theory and a charged lepton mass formula,” Lettere al Nuovo Cimento, 27 (8): 225–228. In my toy model, which I proposed in 1973, I used the Planck time as a quantum of time to replace continuous derivatives with discrete differentiation based on finite differences, which I independently developed while in high school.
 This exegetical interpretation does not contradict nor does it compete with the literal interpretation. This is the allegorical interpretation on the level of remez.