"No; the science professors should live.
They're really great.

But it would be a good deed to break the heads of nine-tenths of the English professors--little, microscopic-minded parrots!" Which was rather severe on the professors, but which to Ruth was blasphemy.

She could not help but measure the professors, neat, scholarly, in fitting clothes, speaking in well-modulated voices, breathing of culture and refinement, with this almost indescribable young fellow whom somehow she loved, whose clothes never would fit him, whose heavy muscles told of damning toil, who grew excited when he talked, substituting abuse for calm statement and passionate utterance for cool self-possession.

They at least earned good salaries and were--yes, she compelled herself to face it--were gentlemen; while he could not earn a penny, and he was not as they.
She did not weigh Martin's words nor judge his argument by them.

Her conclusion that his argument was wrong was reached--unconsciously, it is true--by a comparison of externals.