Sentence:  But the false Fox most kindly played his part, / For whatsoever mother-wit or art / Could work he put in <WSD>proof</WSD>. No practice sly, / No counterpoint of cunning policy, / No reach, no breach, that might him profit bring. / But he the same did to his purpose wring. 
Meaning of the word marked with <WSD> tags:  An effort, process, or operation designed to establish or discover a fact or truth; an act of testing; a test; a trial.