Who is the doctor in The Canterbury Tales and what does he do?
The doctor of physic was grounded in astronomy, (astrology), rather than surgery and medicine; in fact, he taught his patients by using white magic. The doctor thought the cause of illness was related to the humors "hot or cold or moist or dry". He was not a spiritual person as "his study was but little on the Bible", and he was more interested in gold. "He kept what he won" during the plague. Gold could be used in medicine at the time, but, the doctor was more interested in gold's monetary worth, "for gold in physic is a cordial/Therefore he loved gold in special."
The doctor diagnoses people by their horoscopes (aren't you glad our doctors today go by more definitive means?). Once diagnosed, he sends them to the pharmacist with whom he is in cahoots...in other words, they have it worked out where they both make lots of money. Very dishonest.
Here the doctor is very strange. He is a one-sided expert. There was no one who knew about the medicine. He knew astrology and something of nature and could utter the suitable humor to make the patients laugh. He could quote all the medicine authorities, but had little knowledge of the Bible. He had apparently made a lot of money during the plague but does not seem to spend it very readily. He prescribes gold for cures so he has a special love for this metal.
"For gold in physik is a cordial
Therefore he lovede gold in special."