The second and more important reservation is, that although mind and all its qualities are thus indissolubly connected with matter, it by no means follows that they are matter or mere qualities of it. In the case of the atoms and energies, we know absolutely nothing of their real essence, and cannot form even a conception of what they are, how they came there, or what will become of them. It is the same with mind, soul, or self: we feel an instinctive certainty of their existence, as we do of that of matter; and we can trace their laws and manifestations under the conditions in which they are known to us, viz. those of association with matter and motion in the brain. But of their real essence or existence we know nothing, and it is as unscientific to affirm as to deny. Directly we pass beyond the boundary of such knowledge as really can be known by human faculty, and stand face to face with the mystery of the Great Unknown, we can only bow our heads with reverence and say with the poet, Behold, I know not anything. I hope thus to steer safely between Scylla and Charybdis—between the arid rocks of materialism and the whirling eddies of spiritualism. Materialist and spiritualist seem to me very like two men disputing as to the existence of life in the sun. ‘No,’ argues the former; ‘for the known conditions there are totally inconsistent with any life we can conceive.’ ‘Yes,’ says the other; ‘for the belief fits in with many things which I earnestly wish to believe respecting a Supreme Being and a future existence.’ To the first I say, ignorance is not evidence; to the second, wishes are not proofs. For myself, while not quarrelling with those more favoured mortals who have, or fancy they have, superior knowledge, I can only say that I really know nothing; and this being the case, I see no use in saying that I know, and think it both more truthful and more modest to confess the limitation of my faculties.