"There is one other point of comparison which is worth notice. The elementary signs of language are only twenty-six letters, and yet what wonderfully varied meanings can we express and communicate by their combination! Consider, in comparison with this, the enormous number of elementary signs with which the machinery of sight is provided. We may take the number of fibres in the optic nerves as two hundred and fifty thousand. Each of these is capable of innumerable different degrees of sensation of one, two, or three primary colours. It follows that it is possible to construct an immeasurably greater number of combinations here than with the few letters which build up our words. Nor must we forget the extremely rapid changes of which the images of sight are capable. No wonder, then, if our senses speak to us in language which can express far more delicate distinctions and richer varieties than can be conveyed by words."
Finally (pp. 315, 16), "The correspondence, therefore, between the external world and the Perceptions of Sight rests, either in whole or in part, upon the same foundation as all our knowledge of the actual world,—on experience, and on constant verification of its accuracy by experiments which we perform with every movement of our body. It follows, of course, that we are only warranted in accepting the reality of this correspondence so far as these means of verification extend, which is really as far as for practical purposes we need.
"Beyond these limits, as, for example, in the region of Qualities, we are in some instances able to prove conclusively that there is no correspondence at all between sensations and their objects.
"Only the relations of time, of space, of equality, and those which are derived from them, of number, size, regularity of co-existence and of sequence—'mathematical relations' in short, are common to the outer and the inner world, and here we may indeed look for a complete correspondence between our conceptions and the objects which excite them.
"But it seems to me that we should not quarrel with the bounty of nature because the greatness, and also the emptiness, of these abstract relations have been concealed from us by the manifold brilliance of a system of signs; since thus they can be the more easily surveyed and used for practical ends, while yet traces enough remain visible to guide the philosophical spirit aright, in its search after the meaning of sensible Images and Signs."
Let therefore this account of visual Perception be accepted by us, as it will probably be by three-fourths of scientific men throughout Europe. And, next, let us ask, as every real thinker will proceed to ask, on what grounds of certitude rests our assurance as regards the daily and hourly information received through this avenue of perception, reasoned and acted upon with unswerving confidence by us all?
For an examination of the ground principle of Induction, the reader must be referred to our next chapter. But it is at once clear that no human experience can possess the attribute of universality, otherwise it would cease to be human. We have then in this present appeal to the veracity of Experience, no absolute knowledge to deal with, only knowledge as relative to mankind. Nay, we must go a little further still in our limitation, and say to the generality of mankind. For our eyes do not all see perfectly alike—a North-American Indian sees what a Cockney cannot discover; the trained eye discerns differently from the untrained. On the differences of power in eye and ear rest the differences in many kinds of theorising—amongst which art-perceptions yield an obvious and familiar set of examples. And if we try for a more precise estimate of the value of our limited human relativity, and proceed by way of comparison between our own diverse endowments, who shall venture to say that the eye of our body interpreted by our understanding, tells our inmost self more truly than the eye of our human soul, informing us directly of the facts of its intuitive vision? So far as our actual means of valuing these two modes of beholding can go, there is no knowledge so perfect as the product of pure intuition, the glorious fabric of Mathematical Science. And to pure Science it matters not whether the requisite Schematism is drawn upon a sheet of white paper or on the clear tablet of the imagining faculty of a philosopher. The purely inward view is in truth generally the farthest reaching, and the most unclouded. When, therefore, it is, and has been for centuries, apparent to the inmost eye of the generality of our race that there really exists a spiritual world within themselves—above them, and in the far distant future beyond us all, permanent while we change, and the evidence of our own ultimate permanency,—such knowledge may undeniably be human, the very flower and distinction of our human nature; and it may on that account be received by us as true.
If, again, our ordinary human soul is so far a Christian as to exclaim with Tertullian, "O good God," by what logical process shall we confute its utterance, while we maintain the utterance of our commonest sense-perceptions?
That we all see in frames, that we all think in frames, no rational thinker or perceiver will deny. If, however, any of us chooses to be an Idealist or Nihilist, let him at least be consistent;—if he will assert the necessity of Doubt, let him maintain its empire by doubting his own assertion. But let no man think that Doubt leads him any whither except to an abnegation of thought, a mistrust alike of Sense and Soul, and an abdication of every human prerogative:—
"Thy hand, great Anarch, lets the curtain fall,