The otherworldly must behave as prescribed by their stage until the power becomes part of them. Until the potion is digested, the bearer is vulnerable: the power is already there, but control over it is not yet.
The roles of the path are tied to risk and stakes: the bearer puts the outcome on the line again and again and learns to live with what comes up.
The Method long remained the knowledge of the few: the church hierarchs were in no hurry to reveal it, and many otherworldly ascended blindly, paying for it with their sanity.