When I speak of ineffable knowledge, this should be taken literally and not as a designation of mystic experience, to which I do not wish to refer at this stage. Even so my attempt to speak of the ineffable may be thought to be logically meaningless, or alternatively, to offend against the Cartesian doctrine of ‘clear and distinct ideas’ which the early Wittgenstein transposed into terms of semantics in his aphorism: ‘Of what cannot be said’—i.e. said exactly, as a sentence in natural science—‘thereof one must be silent’ … [S]trictly speaking nothing that we know can be said precisely; and so what I call ‘ineffable’ may simply mean something that I know and can describe even less precisely than usual, or even only very vaguely.

Michael Polanyi, Personal Knowledge