Sentence:  It is a very strange thing, and not <WSD>solvable</WSD> by any moral law that I know of, that if a man loses his horse, the whole country will turn out to help hang the thief; but if a man but a shade or two darker than I am is himself stolen, the same crowd will hang one who aids in restoring him to liberty. 
Meaning of the word marked with <WSD> tags:  Capable of being solved.