The _will_ has a wonderful effect upon the perceptive faculties.

When we first look up at the myriads of stars seen in a moonless evening, all is confusion to us; we admire their brilliancy, but we scarcely recognize their grouping.

We do not feel the need of knowing much about them.
"A traveller, lost on a desert plain, feels that the recognition of one star, the Pole star, is of itself a great acquisition; and all persons who, like mariners and soldiers, are left much with the companionship of the stars, only learn to know the prominent clusters, even if they do not know the names given to them in books.
"The daily wants of the body do not require that we should say "'Give me the ways of wandering stars to know The depths of heaven above and earth below.' But we have a hunger of the mind which asks for knowledge of all around us, and the more we gain, the more is our desire; the more we see, the more are we capable of seeing.
"Besides learning to see, there is another art to be learned,--_not to see_ what is not.
"If we read in to-day's paper that a brilliant comet was seen last night in New York, we are very likely to see it to-night in Boston; for we take every long, fleecy cloud for a splendid comet.
"When the comet of 1680 was expected, a few years ago, to reappear, some young men in Cambridge told Professor Bond that they had seen it; but Professor Bond did not see it.

Continually are amateurs in astronomy sending notes of new discoveries to Bond, or some other astronomers, which are no discoveries at all! "Astronomers have long supposed the existence of a planet inferior to Mercury; and M.Leverrier has, by mathematical calculation, demonstrated that such a planet exists.

He founded his calculations upon the supposed discovery of M.Lesbarcault, who declares that it crossed the sun's disc, and that he saw it and made drawings.