Sentence:  I have found , time and again , that some bit of particularly annoying and intractable behavior on the part of a patient rests , in the final analysis , on this basis ; and only when I can acknowledge this , to myself , as being indeed an aspect of my personality , does it cease to <WSD>be</WSD> a prominently troublesome aspect of the patient 's behavior . 
Meaning of the word marked with <WSD> tags:  have the quality of being; (copula, used with an adjective or a predicate noun)