Explore "The Three Taps" by Ronald A. Knox on Textopian. Read with annotations and highlights.
"Now that I have put that fiver on with Bredon, I begin to doubt my own conclusions. That is the extraordinary effect of having a ‘will to believe. ' As long as you have no prejudices in the case, no brief to maintain, you can form a theory and feel that it is a mathematical certainty. Directly you have a reason for wanting to believe the thing true that same theory begins to look as if it had all sorts of holes in it. Or rather, the whole theory seems fantastic -- you have been basing too much on insufficient evidence. Yesterday I was as certain that the case was one of murder as I am certain of my own existence. Today I am developing scruples. Let me get it all down on paper, anyhow; and I shall be able to show my working to Bredon afterward, however the case turns out.
"There is one indication which is absolutely vital, absolutely essential: that is the turning off of the tap. That is the pinpoint of truth upon which any theory must rest. I don't say it's easy to explain the action; but it is an action, and the action demands an agent. The fact that the gas was tampered with would convince me of foul play, even if there were no other direct indications. There are such indications.