The surest kind of knowledge is inner, direct, unmediated - intuitive.
Not a 'communication' - not perceived in words, writing or images (all of which need to be interpreted; there is always a gap between seeing and believing).
But instead occurring in thinking, as knowing. Simple, known-fully and with no gap.
Requiring no 'evidence' because all evidence is uncertain, all inference is prone to error, all reasoning depends on the assuming of mapping reasoning onto reality...
But this is typically ignored, or explained away, nowadays - because modern metaphysics says intuition has zero reality and objectivity.