“Oct. 5.—I can stand it no longer; I have invited Harker to pass a few weeks with me—he has a level head. I can judge from his manner if he thinks me mad. “Oct. 7.—I have the solution of the mystery; it came to me last night—suddenly, as by revelation. How simple—how terribly simple! “There are sounds that we cannot hear. At either end of the scale are notes that stir no chord of that imperfect instrument, the human ear. They are too high or too grave. I have observed a flock of blackbirds occupying an entire tree-top—the tops of several trees—and all in full song. Suddenly—in a moment—at absolutely the same instant—all spring into the air and fly away. How? They could not all see one another—whole tree-tops intervened. At no point could a leader have been visible to all. There must have been a signal of warning or command, high and shrill above the din, but by me unheard. I have observed, too, the same simultaneous flight when all were silent, among not only blackbirds, but other birds—quail, for example, widely separated by bushes—even on opposite sides of a hill. “It is known to seamen that a school of whales basking or sporting on the surface of the ocean, miles apart, with the convexity of the earth between, will sometimes dive at the same instant—all gone out of sight in a moment. The signal has been sounded—too grave for the ear of the sailor at the masthead and his comrades on the deck—who nevertheless feel its vibrations in the ship as the stones of a cathedral are stirred by the bass of the organ. “As with sounds, so with colors. At each end of the solar spectrum the chemist can detect the presence of what are known as ‘actinic’ rays. They represent colors—integral colors in the composition of light—which we are unable to discern. The human eye is an imperfect instrument; its range is but a few octaves of the real ‘chromatic scale.’ I am not mad; there are colors that we cannot see. “And, God help me! the Damned Thing is of such a color!” HAÏTA THE SHEPHERD IN the heart of Haïta the illusions of youth had not been supplanted by those of age and experience. His thoughts were pure and pleasant, for his life was simple and his soul devoid of ambition. He rose with the sun and went forth to pray at the shrine of Hastur, the god of shepherds, who heard and was pleased. After performance of this pious rite Haïta unbarred the gate of the fold and with a cheerful mind drove his flock afield, eating his morning meal of curds and oat cake as he went, occasionally pausing to add a few berries, cold with dew, or to drink of the waters that came away from the hills to join the stream in the middle of the valley and be borne along with it, he knew not whither.