Idries Shah, in The Commanding Self:
Q: How is it that laboratory experiments with extra-sensory perception do not seem to work, even though there is evidence that it does occur outside of the stage situation?
A: For a similar reason to that which applies when you give boiling water to a hen, to make it `lay boiled eggs’. The person who already knows how and why these things work will not attempt to structure the experiment in the way which is adopted by the ordinary experimenter.
We could almost believe that a certain old English rhyme was written to allude to this approach:
Simple Simon went a-fishing
For to catch a whale;
But all the water he had got
Was in his mother’s pail.