A quack is one who pretends to knowledge of which he is ignorant, a charlatan, particularly a medical impostor.
The king himself was indeed a semi-idiot, scarce responsible for his actions, yet his was the era of such striking personalities as the brilliant charlatan Struensee.
Alexander had remarkable beauty and the striking personality of the successful charlatan, and must have been a man of considerable intellectual abilities and power of organization.
The first journal devoted to medicine (1679) was by Nicolas de Blegny, frequently spoken of as a charlatan, a term which sometimes means simply a man of many ideas.
But the pupil soon found his teacher to be a charlatan, and taught himself, aided by commentaries, to master logic, geometry and astronomy.
Opinions are divided as to whether he was a Culdee, a representative of a national Frankish movement, or simply the charlatan that Boniface paints him.
The famous charlatan Cagliostro was also arrested, but it was recognized that he had taken no part in the affair.
Apart from this extravagant eulogy, it is absurd to regard Apollonius merely as a vulgar charlatan and miracle-monger.
Hence the modern sense of empirical as applied to the guess work of an untrained quack or charlatan.
The whole plan was based upon defective information and preconceived ideas; it has gone down to history as a classical example of bad generalship, and its author Weyrother, who was perhaps nothing worse than a pedant, as a charlatan.