Musar zu Bamidbar 8:2

אל מול פני המנורה יאירו שבעת הנרות . We read in Proverbs 20,27, נר ה' נשמת אדם, that "the soul of man is the light of G–d." One needs to see to it constantly that one's soul is lit up through the study of Torah and the performance of מצות. The body of man is somewhat like the shape of the candelabrum. The Menorah had three protrusions on its stem, the arms that extended from its center. It also had a small elevation as its platform. In a similar fashion man's feet, arms and ears are three protrusions. The torso containing the heart is similar to the stem of the Menorah. Its height of 18 handbreadths is equal to the average height of a fully grown person, as stated in Tosaphot in the Talmud Shabbat 92a.

When the twelve princes offered a sacrifice each on the first twelve days after the Tabernacle was erected, they may have intended to counteract the first twelve years of our lives during which we accumulated sins due to the predominance of the evil urge within us. The thirteenth day, on which the Candelabra was first kindled by Aaron (as we read in פרשת בהעלותך after completion of the offerings by the princes), may symbolise the entry of the good urge within us, i.e. from that time onwards the holy flame of spirituality burns within us constantly. The seven lights on the Candelabra symbolise the seven days of the Passover holiday.

Nachmanides pursues the subject at length and provides answers.