details arranged with reference to their real space
order? Should others be added? Can any be omitted? Will the reader form
the mental image you wish him to form?)

+48. Development by Comparison.+--In Section 29 we found that comparison,
whether literal or figurative, aided us in forming mental images of
objects. In a similar way events and general principles may be explained
by making suitable comparisons. We are continually comparing one thing
with another. Every idea tends to recall other ideas that are similar to
it or in contrast with it. When an unfamiliar idea is presented to us we
at once seek to associate it with similar ideas already known to us. A
writer, therefore, will make his meaning clear by furnishing, the desired
comparisons. If these are familiar to us, they enable us to understand
the new ideas presented. Even when both ideas in the comparison are
unfamiliar, each may gain in clearness by comparison with the other.

In comparing two objects, events, or principles we may point out that they
are _not_ alike in certain respects. A comparison that thus emphasizes
differences, rather than likenesses, becomes a contrast. The contrast may
be given in a single sentence or in a single paragraph, but often a
paragraph or more may be required for each of the two ideas contrasted.

EXERCISE

Notice how comparisons and contrasts are used in the following
paragraphs:--

1. Niagara is the largest cataract in the world, while Yosemite is the
highest; it is the volume that impresses you at Niagara, and it is the
height of Yosemite and the grand surroundings that make its beauty.
Niagara is as wide as Yosemite is high, and if it had no more water than
Yosemite has, it would not be of much consequence. The sound of the two
falls is quite different: Niagara makes a steady roar, deep and strong,
though not oppressive, while Yosemite is a crash and rattle, owing to the
force of the water as it strikes the solid rock after its immense leap.

2. It is not only in appearance that London and New York differ widely.
They also speak with different accents, for cities have distinctive
accents as well as people. Tennyson wrote about "streaming London's
central roar"; the roar is a gentle hum compared with the din which
tingles the ears of visitors to New York. The accent of New York is harsh,
grating, jarring. The rattle of the elevated railroad, the whir of the
cable cars, the ringing of electric-car bells, the ru