The cooling planet contracts, it is as if one had some mud in a tin pail, and forced down the lid with such pressure that the can sprung a dozen leaks, or it is as if one had the mud in a linen bag and squeezed; merely as mechanics (not counting that one has all the known and unknown chemical elements cooling simultaneously), but merely as mechanics this contraction gives energy enough to squeeze vegetation through the pores of the imaginary linen and to detach certain particles, leaving them still a momentum. A body should cool with decreasing speed in measure as it approaches the temperature of its surroundings; however, the earth is still, I think, supposed to be warmer than the surrounding unknown, and is presumably still cooling, or at any rate it is not proved that man is at the end of his physical changes. I return to homed gods and the halo in a few paragraphs. It is not proved that even the sort of impetus provided by a shrinking of planetary surface is denied one. What is known is that man's great divergence has been in the making of detached, resumable tools. That is to say, if an insect carries a saw, it carries it all the time. The "next step," as in the case of the male organ of the nautilus, is to grow a tool and detach it. Man's first inventions are fire and the club, that is to say he detaches his digestion, he finds a means to get heat without releasing the calories of the log by internal combustion inside his own stomach. The invention of the first tool turned his mind (using this term in the full sense); turned, let us say, his "brain" from his own body. No need for greater antennæ, a fifth arm, etc., except, after a lapse, as a tour de force, to show that he is still lord of his body. That is to say the langouste's long feelers, all sorts of extravagances in nature may be taken as the result of a single gush of thought. A single out-push of a demand, made by a spermatic sea of sufficient energy to cast such a form. To cast it as one electric pole will cast a spark to another. To exteriorize. Sometimes to act in this with more enthusiasm than caution. Let us say quite simply that light is a projection from the luminous fluid, from the energy that is in the brain, down along the nerve cords which receive certain vibrations in the eye. Let us suppose man capable of exteriorizing a new organ, horn, halo, Eye of Horns. Given a brain of this power, comes the question, what organ, and to what purpose?