In Persona Christi

When I say in the course of a conversation, To be or not to be — that is the question, I quote Shakespeare. But the actor on the stage, pronouncing the same words, does not quote Shakespeare or any of his creations; he rather speaks and acts in the person of Hamlet, whom he personifies. Even more accurately, he does not speak and act in place of Hamlet but rather identifies with him in a certain sense; he speaks and acts as Hamlet.

Christian theology has accepted this particular expression in all innocence in order to emphasize through it the special relationship between the ordained priest and the person of Christ.

— Josef Pieper, In Search of the Sacred

For this reason is it a much more serious matter than simply bad judgment or poor style when the priest at the altar greets the congregation like a good buddy, using some conventional commonplace — something a serious actor, for instance, would never do onstage. The same has to be said regarding the priest who after the liturgy, still dressed in his vestments, joins the chatting groups of people outside the church to discuss the weather and the latest news. An American friend from New Mexico and I had some common experiences in this regard. He was fluent in Spanish and after years of study an expert on this subject. He told me — and this contrasts with the preceding remarks — that the Indians, many of whom were his personal friends, would ignore him as soon as they had donned their ceremonial robes and would not engage in their usual friendly conversation with him.

— Josef Pieper, Ibid.