Which preposition to use with tutoress

of Occurrences 1%

He takes away all the lights of truth in history to make it the fitter tutoress of life; for Truth herself has little or nothing to do in the affairs of the world, although all matters of the greatest weight and moment are pretended and done in her name, like a weak princess that has only the title, and falsehood all the power.

Which preposition to use with  tutoress