This shiur covers Bamidbar Chapter 19, the laws of the Parah Adumah (red heifer) and purification from corpse impurity. The chapter appears out of sequence with the surrounding material about the priestly hierarchy, but connects through the kohen's role in both restricting access to the Mishkan and providing purification for those who became impure. The process involves two parts: first, the ritual slaughter and burning of the red heifer with cedar wood, hyssop, and crimson wool to create purifying ashes; second, the detailed laws of who becomes impure from contact with death and how they must be sprinkled with water mixed with these ashes on the third and seventh days to regain purity.