86 LUCY AMONG THE MOUNTAINS.

daytime, you would find that -you could see but
very little. But if it were possible for you to come
to it in the night, and look in, and yet have daylight
shine. in through the hole in the side, just as be-
fore, you would find that you could see much
better.”

“Pm sure I don’t see why,” said Lucy.

The reason is,” said her mother, “that a
bright light changes the condition of the eye some
how or other, —I don’t know exactly how, but I
know it changes it, — so that it is not so sensitive to
light. So, after we have been walking about in
the bright day, if we go down cellar with a candle,
we can’t see very well. Our eyes have been
‘changed in some way by the great light of the
day, so that we can’t distinguish the objects in
the cellar, which are illuminated only by the dim
light of the candle.”

“If we stay down some time,” said Robert,
“then we can see better.”

“Yes,” said Lucy’s mother, “because then
your eyes become changed again, and adapted to
the faint light. ‘They become more sensitive, and
then, of course, when you come out again into the
bright light of day, they are too sensitive, and you
are dazzled.”