Touch and Sight
Twist the forefinger over the middle finger and touch a small ball with them, so that it may roll between the two fingers, and shut your eyes. You will think that there are two balls. Open your eyes,—and you will see that it is one ball. The fingers have deceived you, but the eyes correct you.
Look (best of all sidewise) at a good, clean mirror,—you will think that it is a window or a door, and that there is something behind it. Touch it with a finger,—and you will see that it is a mirror. The eyes have deceived you, but the fingers correct you.