It is like this: when you try to look in the clearing to join in the with the elves, they vanish. The whole spectacle that you sought to be part of vanishes and you are left to wonder if they were ever there at all.
When we experience these things, we feel we know something happened there, no matter how incoherent. But when we check, or want to check, we check with our tests. And if the tests come up negative, if they show the bell curve, we say ‘nothing is amiss here’. And we feel relieved or cheated until it happens again then we say ‘but there are elves there, I saw them clearly this time.’ ‘And did you gain entry to their party?’ ‘No I did not… and yet I saw them’ still!‘