You shall count for yourselves... from the day on which you bring the Omer offering, seven complete weeks they shall be...
The word sefirah
, "counting", also means "luminance". On each of the 49 days of the Sefirat HaOmer
("Counting of the Omer"), we refine, rarify, and illuminate another of the forty-nine traits of our souls.
(Rabbi DovBer, the Maggid of Mezeritch)