The following letter was written in acknowledgment of a paper by the Reverend E. McClure, which endeavoured to place the belief in an individual permanence upon the grounds that we know of no leakage anywhere in nature; that matter is not a source, but a transmitter of energy; and that the brain, so far from originating thought, is a mere machine responsive to something external to itself, a revealer of something which it does not produce, like a musical instrument.  This “something” is the universal of thought, which is identified with the general logos of the fourth gospel.  Moral perfection consists in assimilation to this; sin is the falling short of perfect revealing of the eternal logos.

Huxley’s reply interested his correspondent not only for the brief opinion on the philosophic question, but for the personal touch in the explanation of the motives which had guided his life-work, and his “kind feeling towards such of the clergy as endeavoured to seek honestly for a natural basis to their faith.”

Hodeslea, Eastbourne, March 17, 1891.

Dear Mr. McClure,

I am very much obliged for your letter, which belongs to a different category from most of those which I receive from your side of the hedge that, unfortunately, separates thinking men.

So far as I know myself, after making due deduction for the ambition of youth and a fiery temper, which ought to (but unfortunately does not) get cooler with age, my sole motive is to get at the truth in all things.

I do not care one straw about fame, present or posthumous, and I loathe notoriety, but I do care to have that desire manifest and recognised.

Your paper deals with a problem which has profoundly interested me for years, but which I take to be insoluble.  It would need a book for full discussion.  But I offer a remark only on two points.

The doctrine of the conservation of energy tells neither one way nor the other.  Energy is the cause of movement of body, i.e. things having mass.  States of consciousness have no mass, even if they can be conceded to be movable.  Therefore even if they are caused by molecular movements, they would not in any way affect the store of energy.

Physical causation need not be the only kind of causation, and when Cabanis said that thought was a function of the brain, in the same way as bile secretion is a function of the liver, he blundered philosophically.  Bile is a product of the transformation of material energy.  But in the mathematical sense of the word “function,” thought may be a function of the brain.  That is to say, it may arise only when certain physical particles take on a certain order.

By way of a coarse analogy, consider a parallel-sided piece of glass through which light passes.  It forms no picture.  Shape it so as to be bi-convex, and a picture appears in its focus.

Is not the formation of the picture a “function” of the piece of glass thus shaped?