Thus heeded, the priest is alone as he enters into the hall that leads into the Holy Temple's interior. No other man could accompany him, for entrance to the area between the hall and the altar or its ramp was forbidden to all but one who was engaged in performing the service. Since this particular aspect of the service was accomplished by only one priest, he entered alone.
He carried no light, but made his way solely by the light of the fire which burned atop the altar. Thus he could not be seen by his colleagues once he entered the hall... for the other priests stood on the eastern side of the court, and this priest now approached the laver which stood on the western side of the altar, to sanctify his hands and feet. Since the altar and ramp were quite high (10 amot - about 5 meters), it blocked all view of him.
This blackout in communications continued, between the priest of the first lottery and his fellows, until he reached the laver - and then, the others finally knew his position; not by sight, but by sound...