Christine Hayes, in this Yale lecture from her course Introduction to the Old Testament (Hebrew Bible), introduces the Priestly source (P) found chiefly in Leviticus and Numbers. She walks through the symbolism of the Israelite sanctuary, the Priestly conception of holiness and time, and the distinction between moral and ritual impurity. The lecture covers ritual purification, sacrifices and offerings, and the idea of imitatio dei, human imitation of God, as the basis for Priestly ethics. Later sections examine how moral impurity is understood to defile the land itself and how it can be purified, before closing with the dietary laws and the Holiness Code. Recorded in Fall 2006 as part of Yale's RLST 145, the talk lays out P's theological system as a coherent alternative to the narrative sources studied earlier in the course.