is not so obvious, and there is danger of its escaping notice. One hears the line with increased pleasure after the imitation of sound is pointed out; but only the trained ear catches it at first.

This correspondence of sound and sense is called onomatopoeia. It may appear in a single word, as buzz, whack, crackle, roar, etc.; or a combination of imitative words, as Tennyson's

The moan of doves in immemorial elms,
And murmuring of innumerable bees;

or a suggestive echo rather than direct imitation, as Shelley's

Makes faint with too much sweet these heavy-wingèd thieves;

or a suggestion of motion rather than of sound, as Milton's sea-fish

huge of bulk,
Wallowing unwieldy, enormous in their gait,

and the

Leviathan, which God of all his works
Created hugest that swim the ocean stream;