Thereupon of course comes up the paradox and mystery: If the knowledge of toothache be pent up in this separate mental pocket, how can it be known cum alio or brought into one view with anything else? This pocket knows nothing else; no other part of the mind knows toothache.The knowing of toothache cum alio must be a miracle.And the miracle must have an Agent.And the Agent must be a Subject or Ego 'out of time,' -- and all the rest of it, as we saw in Chapter X.And then begins the well-worn round of recrimination between the sensationalists and the spiritualists, from which we are saved by our determination from the outset to accept the psychological point of view, and to admit knowledge whether of simple toothaches or of philosophic systems as ultimate fact.There are realities and there are 'states of mind,' and the latter know the former; and it is just as wonderful for a state of mind to be a 'sensation' and know simple pain as for it to be a thought and know a system of related things.
But there is no reason to suppose that when different states of mind know different things about the same toothache, they do so by virtue of their all containing faintly or vividly the original pain.Quite the reverse.The by-gone sensation of my gout was painful, as Reid somewhere says; the thought of the same gout as bygone is pleasant, and in no respect resembles the earlier mental state.
Sensations, then, first make us acquainted with innumerable things, and then are replaced by thoughts which know the same things in altogether other ways.And Locke's main doctrine remains eternally true, however hazy some of his language may have been, that "though there be a great number of considerations wherein things may be compared one with another, and so a multitnde of relations; yet they all terminate in , and are concerned about, those simple ideas either of sensation or reflection, which I think to be the whole materials of all our knowledge....The simple ideas we receive from sensation and reflection are the boundaries of our thoughts;
beyond which, the mind whatever efforts it would make, is not able to advance one jot; nor can it make any discoveries when it would pry into the nature and hidden causes of those ideas."
The nature and hidden causes of ideas will never be unravelled till the next between the brain and consciousness is cleared up.All we can say now is that sensations are first things in the way of consciousness.Before perceptions can come, sensations must have come; but sensations come, no psychic fact need have existed, a current is enough.If the nerve-current be not given, nothing else will take its place.To quote the good Locke again:
"It is not in the power of the most exalted wit or enlarged understanding, by any quickness or variety of thoughts, to invent or frame one new simple idea in the mind...I would have any one try to fancy any taste which had never affected his palate, or frame the idea of a scent he had never smelt; and when he can do this, I will also conclude that a blind man hath ideas of colors, and a deaf man true distinct notions of sounds."
The brain is so made that all currents in it run one way.Consciousness of some sort goes with all the currents, but it is only when new currents are entering that it has the sensational tang.And it is only then that consciousness directly encounters (to use a word of Mr.Bradley's) a reality outside itself.
The difference between such encounter and all conceptual knowledge is very great.A blind man may know all about the sky's blueness, and I may know all about your toothache, conceptually;
tracing their causes from primeval chaos, and their consequences to the crack of doom.But so long as he has not felt the blueness, nor I the toothache, our knowledge, wide as it is, of these realities, will be hollow and inadequate.
Somebody must feel blueness, somebody must have toothache, to make human knowledge of these matters real.Conceptual systems which neither began nor left off in sensations would be like bridges without piers.Systems about fact must plunge themselves into sensation as bridges plunge their piers into the rock.Sensations are the stable rock, the terminus a quo and the teminus ad quem of thought.To find such termini is our aim with all our theories -- to conceive first when and where a certain sensation maybe had, and then to have it.Finding it stops discussion.
Failure to find it kills the false conceit of knowledge.Only when you deduce a possible sensation for me from your theory, and give it to me when and where the theory requires, do I begin to be sure that your thought has anything to do with truth.
Pure sensations can only be realized in the earliest days of life.They are all but impossible to adults with memories and stores of associations acquired.Prior to all impressions on sense-organs the brain is plunged in deep sleep and consciousness is practically non-existent.Even the first weeks after birth are passed in almost unbroken sleep by human infants.It takes a strong message from the sense-organs to break this slumber.In a new-born brain this gives rise to an absolutely pure sensation.But the experience leaves its 'unimaginable touch' on the matter of the convolutions, and the next impression which a sense-organs transmits produces a cerebral reaction in which the awakened vestige of the last impression plays its part.Another sort of feeling and a higher grade of cognition are the consequence; and the complication goes on increasing till the end of life, no two successive impressions falling on an identical brain, and no two successive thoughts being exactly the same.(See above, p.230 ff.)
