Sentence:  In the old days, to my commonplace and unobserving mind, he gave no evidences of genius whatsoever. He never read me any of his manuscripts, [...], and therefore my lack of <WSD>detection</WSD> of his promise may in some degree be pardoned. 
Meaning of the word marked with <WSD> tags:  The act of detecting or sensing something; discovering something that was hidden or disguised.