Sentence:  However , readers who accept Freud 's findings and believe that he has solved completely the mystery of dreams , should ponder over the following words in his Interpretation Of Dreams , Chapter 1 , : `` as a matter of fact no such complete solution of the dream has ever been accomplished in any case , and what is more , every one attempting such solution has found that in most cases there have remained a great many components of the dream the source of which he has been <WSD>unable</WSD> to explain , nor is the discussion closed on the subject of the mantic or prophetic power of dreams '' . 
Meaning of the word marked with <WSD> tags:  (usually followed by `to') not having the necessary means or skill or know-how