Sentence:  The conclusion of this discussion must be that Nietzsche's “<WSD>revaluation</WSD> of values” is a most complex matter, and there is no single answer to the question as to what he was attacking or as to what the basis might be for the attack. 
Meaning of the word marked with <WSD> tags:  A reassessment of the value or worth of something; a reappraisal or reevaluation.