A teacher in class is
like a man in the woods at night with a powerful flashlight in his hand.
Wherever he turns his light, the creatures on whom it shines are aware of it,
and do not behave as they do in the dark. Thus the mere fact of his watching
their behavior changes it into something very different. Shine where be will,
he can never know very much of the night life of the woods.

Autore: John C. Holt