Sentence:  Particularly hard for the therapist to grasp are those instances in which the patient is manifesting an introject <WSD>traceable</WSD> to something in the therapist , some aspect of the therapist of which the latter is himself only poorly aware , and the recognition of which , as a part of himself , he finds distinctly unwelcome . 
Meaning of the word marked with <WSD> tags:  (usually followed by `to') able to be traced to