Musar sobre Números 18:23

The instruction in 12,19: השמר לך פן תעזוב את הלוי כל ימיך על אדמתיך, "Be careful not to neglect the Levite as long as you live on your land," is similarly based on the perception of the Levite as the sacrifice. We know that Isaac represents the מדת הדין, the attribute of Justice, i.e. a person whom G–d could deal with on the basis of his near-perfection. We know that the Levite was not allowed to offer the sacrifices on the altar; yet he is repeatedly referred to as performing עבודה. In connection with the sacrifices the Torah always uses the Ineffable four-lettered Name, an allusion to the attribute of Mercy. There is the further fact that the Torah describes the Levites as put at the disposal of Aaron the Priest and his sons (Numbers 8,19); the latter represented the מדת החסד, the attribute of Mercy. However, this is an indication that in this instance the attribute of Justice is used to "sweeten" the attribute of Mercy by uniting with it. עבודה and תורה go hand in hand; we know this from Deut. 33,10 where the task of the Levites to teach Israel the Torah is outlined. In practical terms, the sacrificial service, עבודה, was always accompanied by readings from the מעשה בראשית (Taanit 27). The members of the tribe of Levi were the principal teachers of Torah amongst the people. The gifts the Torah sets aside for the Levites are designed to free the Levites from the burden of having to earn a living. They then can devote themselves to their principal task of disseminating Torah knowledge. We have explained two of the three "pillars" on which the continued existence of the universe depends, i.e. תורה ועבודה.