Perceiving With Emunah
Likutei Halachos on Parshas Vaeschanan
Translated by Dov Grant
Devarim 4:6 "…for it is your wisdom and understanding in the eyes of the nations…"
Chazal tell us that this verse refers to the calculation of the “seasons and constellations”, i.e. the determination of the start of the Jewish lunar months [when the moon starts to wax again after a two week period of waning]. This is the time when there is “filling of the blemish of the moon so that it exhibit no lack and that its light be as the sun” (prayer of kiddush levanah). This alludes to emunah/faith becoming full and complete with a completion without blemish or lack at all, becoming as the light of the sun.
This means that we must try to be very strong in our emunah – which relates to the moon – in matters that the intellect is unable to comprehend and attain. Emunah should be so powerful within us, and so illuminate the intellect, as if we actually see and understand intellectually. This is the main way of complete emunah: It should appear to us as if we are really looking, with our eyes. This is the concept of the “light of the moon as that of the sun”.
Orach Chaim Hilchos Rosh Chodesh 6:1