Parashat Emor | The Meaning of the Jewish holidays

This parasha seems to deal with the typical topics of the Book of Vayikra: the special laws for the priests, impurity vs. purity, sacrifices etc. However, there is a sudden change, and the Torah moves on to discuss the commandments and sacrifices of the holidays. What is the meaning of this shift and why are the Sabbath and the holidays brought up here?