Which preposition to use with discerner

of Occurrences 8%

Now, Madame de Maintenon, whatever her defects, her pharisaism, her cunning, her ambition, and her narrow religious intolerance, was still, it would seem, always respected, not only by the King himself,a great discerner of character,but by the court which she controlled, and even by that gay circle of wits who met around the supper-tables of her first husband.

Which preposition to use with  discerner