Time is both discontinuous and cyclical.
For example, every day there are two cycles of twelve hours forming the hours of the day and the hours of the night.
But no given hour is like another.
Each has its own life, dimension, and tonality.
According to kabbalists this reflects the twelve different configurations of the four letters of the Tetragrammaton.
Each hour is governed by one of these configurations.
In other words, each hour has its own code, a unique code, just the way each instant is unique.
The second cycle is the cycle of days.
Here again each day forms a complete cycle, a self-contained entity, and each morning is a new birth.
This explains the importance of the prayer that celebrates this birth.
In a similar fashion, the week has its cycle, and the month, whose birth is connected to the moon.
Finally, we have the cycle of the year.
However, there is a fundamental difference between this cycle and the others.
All the other temporal organizations are cyclical, but Rosh Hashanah is an absolute beginning.
Recall that shanah ("year") comes from a root that means "doubling," "repetition."
Indeed, what happens is a repetition of the act of creation and a total renewal of time.
–Rabbi Adin Steinsaltz
From The Seven Lights, p. 11, by Rabbi Adin Steinsaltz