when, for the first time, he heard the voice of the priest.

A powerful and experienced voice. It pierced through the reaches of the cathedral ready waiting for it! But the priest was not calling out to the congregation, his cry was quite unambiguous and there was no escape from it, he called “Josef K.!”

K. stood still and looked down at the floor. In theory he was still free, he could have carried on walking, through one of three dark little wooden doors not far in front of him and away from there. It would simply mean he had not understood, or that he had understood but chose not to pay attention to it. But if he once turned round he would be trapped, then he would have acknowledged that he had understood perfectly well, that he really was the Josef K.