rceive how great
a number of mankind may be partially incapacitated from either
discovering or feeling it.

Sec. 5. And of the intellectual powers.

Sec. 6. How sight depends upon previous knowledge.

Next to sensibility, which is necessary for the perception of facts,
come reflection and memory, which are necessary for the retention of
them, and recognition of their resemblances. For a man may receive
impression after impression, and that vividly and with delight, and yet,
if he take no care to reason upon those impressions and trace them to
their sources, he may remain totally ignorant of the facts that produced
them; nay, may attribute them to facts with which they have no
connection, or may coin causes for them that have no existence at all.
And the more sensibility and imagination a man possesses, the more
likely will he be to fall into error; for then he will see whatever he
expects, and admire and judge with his heart, and not with his eyes. How
many people are misled, by what has been said and sung of the serenity
of Italian skies, to suppose they must be more _blue_ than the skies of
the north, and think that they see them so; whereas, the sky of Italy is
far more dull and gray in color than the skies of the north, and is
distinguished only by its intense repose of light. And this is confirmed
by Benvenuto Cellini, who, I remember, on his first entering France, is
especially struck with the clearness of the sky, as contrasted with the
_mist_ of Italy. And what is more strange still, when people see in a
painting what they suppose to have been the source of their impressions,
they will affirm it to be truthful, though they feel no such impression
resulting from it. Thus, though day after day they may have been
impressed by the tone and warmth of an Italian sky, yet not having
traced the feeling to its source, and supposing themselves impressed by
its _blueness_, they will affirm a blue sky in a painting to be
truthful, and reject the most faithful rendering of all the real
attributes of Italy as cold or dull. And this influence of the
imagination over the senses, is peculiarly observable in the perpetual
disposition of mankind to suppose that they _see_ what they _know_, and
_vice versa_ in their not seeing what they do not know. Thus, if a child
be asked to draw the corner of a house, he will lay down something in
the form of the letter T. He has no conception that the two lines of the
roof, which he knows