Association of ideas is the principle underlying figurative expressions.  By a figure of speech a writer shows his readers the relation between a new idea and one already familiar to them.  An unfamiliar object, for example, is likened to a familiar one, directly, as in the simile, or by implication, as in the metaphor.  As the object brought into relation with the new idea is more familiar and more concrete, the effect of the figure is to simplify the subject that is being explained, and to make it more easy of comprehension.

A figure of speech makes both for conciseness and for economy of mental effort on the part of the reader.  To say in a personality sketch, for example, that the person looks “like Lincoln” is the simplest, most concise way of creating a mental picture.  Or to describe a smoothly running electric motor as “purring,” instantly makes the reader hear the sound.  Scores of words may be saved, and clearer, more vivid impressions may be given, by the judicious use of figures of speech.

As the familiar, concrete objects introduced in figures frequently have associated emotions, figurative expressions often make an emotional appeal.  Again, to say that a person looks “like Lincoln” not only creates a mental picture but awakes the feelings generally associated with Lincoln.  The result is that readers are inclined to feel toward the person so described as they feel toward Lincoln.

Even in practical articles, figurative diction may not be amiss.  In explaining a method of splitting old kitchen boilers in order to make watering troughs, a writer in a farm journal happily described a cold chisel as “turning out a narrow shaving of steel and rolling it away much as the mold-board of a plow turns the furrow.”

The stimulating effect of a paragraph abounding in figurative expressions is well illustrated by the following passage taken from a newspaper personality sketch of a popular pulpit orator: 

His mind is all daylight.  There are no subtle half-tones, or sensitive reserves, or significant shadows of silence, no landscape fading through purple mists to a romantic distance.  All is clear, obvious, emphatic.  There is little atmosphere and a lack of that humor that softens the contours of controversy.  His thought is simple and direct and makes its appeal, not to culture, but to the primitive emotions. * * * * His strenuousness is a battle-cry to the crowd.  He keeps his passion white hot; his body works like a windmill in a hurricane; his eyes flash lightnings; he seizes the enemy, as it were, by the throat, pommels him with breathless blows, and throws him aside a miserable wreck.

SENTENCES.  For rapid reading the prime requisite of a good sentence is that its grammatical structure shall be evident; in other words, that the reader shall be able at a glance to see the relation of its parts.  Involved sentences that require a second perusal before they yield their meaning, are clearly not adapted to the newspaper or magazine.  Short sentences and those of medium length are, as a rule, more easily grasped than long ones, but for rapid reading the structure of the sentence, rather than its length, is the chief consideration.  Absolute clearness is of paramount importance.