Final answer:
Before stepping inside the inner sanctum, several requirements need to be met, including sacrifices, purification, procession, and adherence to specific rules.
Step-by-step explanation:
Before stepping inside the inner sanctum, several requirements need to be met. First, there may be preliminary sacrifices and purifications, possibly with water from the fountain. Then, initiands and priests would enter the sanctuary in procession. They would pass through a rectangular enclosure with an altar, where they would purify themselves. Once inside, they would follow specific rules, such as placing lustral basins in the sanctuary and avoiding certain areas.