When does the moon have no light for us? When it is closest to the sun.

The closer it comes to alignment between us and the sun, the more it diminishes in size. Until, at its closest point, it altogether disappears. Then, once again, it is renewed and begins to shine.

At those points in life when we peer into darkness, groping to understand why this is happening to us, where this is taking us, why this must happen to us . . .
—those are the points of closeness to the light,
those are the points of renewal.

Sefer Hasichot 5752, vol. 1, pp. 157‐158.