wheat_, 'sift' is a live metaphor; in _the sifting of evidence_, the
metaphor is so familiar that it is about equal chances whether
_sifting_ or _examination_ will be used, and a sieve is not present to
the thought--unless, indeed, some one conjures it up by saying _All
the evidence must first be sifted with acid tests_, or _with the
microscope_; under such a stimulus our metaphor turns out to have been
not dead, but dormant. The other word, _examine_, will do well enough
as an example of the real stone-dead metaphor; the Latin _examino_,
being from _examen_ the tongue of a balance, meant originally to
weigh; but, though weighing is not done with acid tests or microscopes
any more than sifting, _examine_ gives no convulsive twitchings, like
_sift_, at finding itself in their company; _examine_, then, is dead
metaphor, and _sift_ only half dead, or three-quarters.

2. Some pitfalls. A, Unsustained Metaphor; B, Overdone Metaphor; C,
Spoilt Metaphor; D, Battles of the Dead; E, Mixed Metaphor.

A. Unsustained Metaphor

_He was still in the middle of those twenty years of neglect which
only began to lift in 1868_. The plunge into metaphor at _lift_, which
presupposes a mist, is too sudden after the literal _twenty years of
neglect_; years, even gloomy years, do not lift.

_The means of education at the disposal of the Protestants and
Presbyterians of the North were stunted and sterilized._ 'The means at
disposal' names something too little vegetable or animal to consort
with the metaphorical verbs. Education (personified) may be stunted,
but means may not.