Pass the tip of your finger over the Moth’s head. You will feel a few very rough wrinkles. The magnifying-glass shows us more. We find, between the eyes and higher up, four or five transversal scales, so set as to overlap one another; they are hard and black and are trimmed crescent-wise at the ends. The longest and strongest is the uppermost, which is in the middle of the forehead. There you have the centre-bit of your boring-tool. To make our tunnels in granitic rocks we tip our drills with diamond points. For a similar task the Bombyx, a living drill, wears implanted on her forehead a row of crescents, hard and durable as steel, a regular twist-bit. Without suspecting its use, Réaumur was perfectly aware of this marvellous implement, which he called scaly stairs: “What does it profit this Moth,” he asks, “that she should thus have the front of her head formed like scaly stairs? That is just what I do not know.” My test-tubes, learned master, will tell us. By good fortune, of the numerous Moths ascending from the bottom of my apparatus through a column of sand solidified by the evaporation of the original moisture, some are making their way upwards against the side of the tube, enabling me to follow their manœuvres. I see them raising their cylindrical bodies, butting with their heads, jerking now in one direction, now in another. The nature of their task is obvious. The centre-bits, with an alternating movement, are boring into the agglutinated sand. The powdery wreckage trickles down from overhead and is at once thrust backward by the legs. A little space forms at the top of the vault; and the Moth moves so much nearer to the surface. By the following day, the whole column, ten inches in height, will be perforated with a straight, perpendicular shaft. Shall we now form an idea of the total work performed? Let us turn the test-tube upside down. The contents, as I have said, will not fall out, for they have set into a block; but from the tunnels bored by the Moth trickles all the sand crumbled by the crescents of the drill. The result is a cylindrical gallery, of the width of a lead-pencil, very cleanly cut and reaching to the bottom of the solid mass. Are you satisfied, my master? Do you now perceive the great utility of the scaly stairs? Would you not say that we have here a magnificent example of an instrument superlatively fitted for a definite task? I share this opinion, for I think, with you, that a sovereign Reason has in all things coordinated the means and the end. But let me tell you: we are called old-fashioned, you and I; with our conception of a world ruled by an Intelligence, we are quite out of the swim. Order, balance, harmony: that is all silly nonsense. The universe is a fortuitous arrangement in the chaos of the possible. What is white might as easily be black, what is round might be angular, what is regular might be shapeless and harmony might just as well be discord. Chance has decided all things.