Clowns are cavorting to the music, children are clamoring for sweets, people are lining up to be frightened or thrilled or amused. Another day in the glorious theme park of life.

Do you take the Ferris wheel or the roller coaster?

If you’re a Ferris wheel kind of guy, you want your ups and downs to follow an even cycle. You acknowledge that life is a ride—that there are times to ascend and times to descend, times to move and times to halt, and times to sway gently in the breeze. But you need for it to follow a regular pattern, so that you can reflect on what has been and prepare for what’s to come.

If you opt for the roller coaster, it’s because you know that the real fun comes when you’re caught unawares. When you inch up a long, seemingly endless incline, only to plunge into a bottomless pit; when a slow, graceful somersault follows a twisting hurdle through dark tunnels. When you never know what the ride will throw at you next, and have only your grip on the handlebar and your faith in the designer’s ingenuity to get you through it.

Another day in the theme park of life. Do you take the Ferris wheel or the roller coaster?

Did you ever wonder why our calendar has both weeks and months? Why follow two different cycles that never match up?

The week came first. As the Bible tells it, G‑d created the world in seven days—six days of work and a seventh of rest. According to the Kabbalists, everything in creation is modeled upon a structure of seven sefirot (“lights” or “spheres”)—including time itself. The weekly Shabbat, first observed by Adam only hours after his creation, is thus the key to living our lives as “partners with G‑d in creation,” of attuning our own creative powers with those of our Creator.

In other words, the seven-day week is nature’s inner clock—the system by which it was brought into being, and by which it continues to be sustained and maintained by its Creator.

And then, one dark night in Egypt some 2,448 years after the first Shabbat, the month was born.

And G‑d spoke to Moses and to Aaron in the land of Egypt, saying: “This new moon shall be for you the head of months, the first of the month of the year for you . . .” (Exodus 12:1–2)

The week is generated by seven sunsets and seven sunrises, a repetitive event by which each day in the cycle is virtually indistinguishable from its fellows; the month, on the other hand, has its progress marked by the moon’s phases, as it grows from crescent to fullness, only to dwindle back to oblivion and await another rebirth. The week was programmed by the Creator into creation; the month, on the other hand, must be created anew each time—according to Torah law, a new month is proclaimed only after the Sanhedrin (supreme court) hears testimony from two witnesses who saw the new moon. Shabbat, which commemorates the creation of the natural order, is a product of the week; the festivals that commemorate the miracles of Jewish history (Passover, Sukkot, Chanukah, Purim, etc.) are all products of the month.

If the week represents all that is regular and immutable in our world, the month represents the new, the unanticipatable, the miraculous.

Do you take the Ferris wheel or the roller coaster? Imagine that you could ride both simultaneously. If you can imagine that, you know the experience of living with the Jewish calendar.