At this point I feel it necessary to declare in advance that the ideas considered in this section are not meant to have the same logical force as what has gone before, but that I regard their ethical importance as much greater. I will freely and frankly admit at the outset that, from now on, not only am I not going to refrain from metaphysics, nor even from mysticism, but that they play an essential part in all that follows. Of course, I know perfectly well that this admission alone is enough to call down upon me a violent attack from the rationalist quarter, that is, from the majority of my scientific colleagues, from whom the most I can hope is that they will say, with a gently mocking smile: ‘Don't impose that on us, my dear fellow; you know, it makes us very much more inclined than ever to accept the extremely obvious explanation of a material world as the cause of our common experience; it's unartificial, it's accepted quite simply by everybody, and it has absolutely nothing metaphysical or mystical about it.’

Against this anticipated attack my defence consists in a no less amicable counter- or preventive attack, namely, that the assertion italicised above is mistaken.