Coincidences, in general, are great stumbling-blocks in the way of that class of thinkers who have been educated to know nothing{q} of the theory of probabilities
I am not quite sure about the meaning of this sentence, is it means that normal people over interpreting the coincidences as the motivation of murderer?
They must, then, have the power of fastening themselves
I think the detective is smart. When he find the sash is difficult to be opened and needed to be fasten inside, he doesn’t quit the possibility that murderer could escape from the window but try to find if the window can fasten by itself.
in whose tones, even, denizens of the five great divisions of Europe could recognise nothing familiar! You will say that it might have been the voice of an Asiatic
When it comes to the crime, we will assume that it is committed by human, so the unusual sound could be interpreted as the terrified scream of the women or the shout of the murder; however, it couldn’t be recognized as any kinds of language, implying that the murderer might not be a human.