"But the fact that millions of birds not accustomed to flying cannot fly over great spaces of water or Alpine glaciers, does not explain the autumn flight of the corn-crakes.
"Since this cannot be explained on natural grounds, it is supernatural. We must accordingly admit that we believe sometimes on the supernatural, or on miracles.
"From this proved thesis you can deduce the corollaries for yourself if you possess the faculty of drawing inferences."
Phantasms which Are Real.—The teacher asked: "Can one see a phantasm?"
"What is a phantasm?"
"There are in optics real images which can be caught on a screen. An image reflected in a flat mirror cannot be caught upon a screen, and is therefore a phantasm. Can you see your image in a flat mirror?"
"Yes."
"Then you can see a phantasm, or an unreal image. The eye, therefore, is a skilful instrument, which can make the unreal real. One might thus be tempted to believe in ghosts."
"What are ghosts?"
"They are phantasms, or unreal images which the eye can take in at certain distances. Great and credible men, such as Luther, Swedenborg, and Goethe, have seen ghosts."