“Time is money” goes the famous expression. But the Chofetz Chaim lived by the opposite credo. He once expressed regret over the purchase of a sefer he didn’t really need: “seforim iz gelt, un gelt iz tzeit, un tzeit iz leben — seforim cost money, and money is time, and time is life.”

Ever cognizant that This World is the passageway to Olam Haba, the Chofetz Chaim viewed every decision, large and small, through this lens. Every moment of life was a gift of priceless potential, and a purchase was not only an expenditure of money, but, more importantly, an outlay of time —the time spent in order to make that money.

Marking Time

If time is indeed a valuable gift, it needs to be secured, cherished, savored. Hashem provided us with a system to mark the passage of time as a reminder to utilize this precious commodity well. On the fourth day of creation, He created the celestial luminaries to measure the “days and years” (Bereishis 1:14). Thus, day and night are defined by the rising and setting of the sun, months are measured by the moon’s orbit of the earth, and the yearly cycle of seasons is affected by the sun’s travels.

What about the weeks? Why is time divided into seven-day intervals? In contrast to other units of time, the week is unrelated to any astronomical phenomenon but it, too, originated at the very beginning of time. It’s unlikely that a human being would have ever made this choice. As far as numbers go, seven seems, well, inelegant and unwieldy. It is not an even number such as two or six, nor a perfect square like four or nine, nor a common base like five or ten.

Not only did Hashem specifically choose the number seven to mark time, but seven occurs throughout Hashem’s creations: in the natural world, in the lives of humans, and in the mitzvos of the Torah. A week is seven days, the shemittah cycle is seven years, there are seven heavens and seven seas, and Eretz Yisrael, the land of seven nations, is blessed with shivas haminim. There are seven different notes in a musical scale (the eighth is a repeat of the first) and seven colors in the rainbow. Many life-cycle events and rituals last seven days: the seven days of sheva brachos, the seven days of mourning for a close relative, and the seven days of purification for tzaraas and other impurities.

The links between the month of Tishrei and the number seven are many: Tishrei is referred to in the Torah as “the seventh month.” During the Yom Kippur avodah, the blood of certain korbanos is sprinkled repeatedly, in groups of seven, toward the Aron, the Paroches, and upon the Mizbeiach Hazahav, and we end our prayers on this solemn day with seven cries of “Hashem Hu haElokim.”

Succos is a seven-day festival and seven Ushpizim visit our succah. The succah is reminiscent of the seven clouds of glory that protected us in the midbar. The Midrash lists seven mitzvos of Succos: the four minim, the succah, the mitzvah of Chagigah, and the mitzvah of simchah. The seventh day of Succos is Hoshana Rabbah, an esoteric and awe-inspiring day when we circle the bimah seven times with our hoshanos. Similarly, we dance seven circuits, or hakafos, with the Torah on Simchas Torah.

The Uniqueness of Seven

Why did Hashem choose the number seven? To fully understand the phenomenon of seven, we need to revisit Pesach (another seven-day Yom Tov, which also has a celebrated seventh day, Shevii shel Pesach) and listen to the lively choruses that punctuated the closing moments of our Seder.