This excerpt is by the biologist
J.B.S. Haldane. I looked this up after hearing about it anecdotally in
The Ancestor's Tale:
The barnacle, then, finds as great a difficulty in unifying its visual and tactile space as an astronomer in calculating the distances of the stars. In fact; the average sensual barnacle regards the attempt to do so as ludicrous and presumptuous. 'The world,' it says is what we can sweep with our arms. Things come into it, and my visions are of some use to me in telling me of things that will come into being in it, but they are notoriously deceptive. I know that when a vision becomes very large it is time for me to shut my shell, though sometimes even a very large vision does not portend any real event. But that rule of conduct was revealed to us by the Great Barnacle ages ago; and was not discovered by the philosophers: also know that when I have a vision in a certain direction, a real thing will sometimes come into being within range of my fourth left arm, and so on. But it seldom does, or I should be fatter than I am! I do not think that we are helped in any way by calling visions "near" if they precede the advent of a real thing, and "far" if they do not. Visions are visions and realities are realities, and no good will come of mixing them up. A philosopher on the next rock was telling his neighbours that a large vision was "far" and not dangerous, when a thing came into being and nipped six of his arms of. His neighbours had all shut up, and he got little pity from them!' Nevertheless, a number of earnest barnacles have formed a society for the investigation of visions. They find that though they generally agree in seeing a vision at the same time, they often differ about its shape and direction. The sceptics say that this proves that visions are nonsense. The members of the S.V.R. (Society for Visionary Research) have recorded many series of partial correspondences between visions of different individuals, and believe that they are on the track of some law governing them. Unfortunately, they are handicapped by two causes besides scepticism. A number of barnacles hold that after a barnacle has died it becomes a vision; while others, 'inspired by a love of gain or notoriety, make claims which can hardly be substantiated to seeing visions. So on the whole the sensible barnacle considers that there is nothing real out of range of his own or his neighbour's arms. Some of them would qualify this by a statement that bad barnacles when they die go to a rock where it is always low tide, while the virtuous are planted near the opening of an immense sewer, where food is carried to their mouths without any effort on their part. But the idea that so fixed and respectable an animal should be transformed into a vision, which is not on unsubstantial, but mobile, they regard as merely disgusting.
I thought that this was a fable worthy of some reflection. Haldane was the same to write that "the world is not only queerer than we suppose, it is queerer than we
can suppose." The analogy makes it easier to imagine at least a few ways in which this might be so. Excuse him the sexist language, it was 1932:
Man is after all only a little freer than a barnacle. Our bodily and mental
activities are fairly rigidly confined to those which have had survival
value to our ancestors during the last few million generations. Our own
appraisement of these activities is dictated to some extent by other
considerations than their survival value, but their nature is limited by
our past. We have learned to think on two different lines - one which enables
us to deal with situations in which we find ourselves in relation to our
fellow-men, another for corresponding situations with regard to inanimate
objects. We are pretty nearly incapable of any other types of thought.
More of the text can be found
here.