The doctor is sitting at his desk in front of an open book. He looks pretty much like the authority who introduces La Danse Macabre (picture to the left) and who wraps up the story at the end. The biggest difference is the vegetation surrounding the authority, showing — oddly — that he is seated outdoors among the other dancers.
Another difference is that this "doctor" is not an all-knowing authority, but is just another victim of Death's arrows.
Master, who has so many books:
Your science does not take into account
if you are not freed from sin
276 when you give account before God.
"compte", which can mean both "to count" and "account", is another example of an "equivocal rhyme". But who's counting?