Don't use mixed metaphors, that is, different metaphors in relation to the same subject: "Since it was launched our project has met with much opposition, but while its flight has not reached the heights ambitioned, we are yet sanguine we shall drive it to success." Here our project begins as a ship, then becomes a bird and finally winds up as a horse.
Personification (from the Latin persona, person, and facere, to make) is the treating of an inanimate object as if it were animate and is probably the most beautiful and effective of all the figures.
"The mountains sing together, the hills rejoice and clap their hands."
"Earth felt the wound; and Nature from her seat,
Sighing, through all her works, gave signs of woe."
Personification depends much on a vivid imagination and is adapted especially to poetical composition. It has two distinguishable forms: (1) when personality is ascribed to the inanimate as in the foregoing examples, and (2) when some quality of life is attributed to the inanimate; as, a raging storm; an angry sea; a whistling wind, etc.
An Allegory (from the Greek allos, other, and agoreuein, to speak), is a form of expression in which the words are symbolical of something. It is very closely allied to the metaphor, in fact is a continued metaphor.
Allegory, metaphor and simile have three points in common,—they are all founded on resemblance. "Ireland is like a thorn in the side of England;" this is simile. "Ireland is a thorn in the side of England;" this is metaphor. "Once a great giant sprang up out of the sea and lived on an island all by himself. On looking around he discovered a little girl on another small island near by. He thought the little girl could be useful to him in many ways so he determined to make her subservient to his will. He commanded her, but she refused to obey, then he resorted to very harsh measures with the little girl, but she still remained obstinate and obdurate. He continued to oppress her until finally she rebelled and became as a thorn in his side to prick him for his evil attitude towards her;" this is an allegory in which the giant plainly represents England and the little girl, Ireland; the implication is manifest though no mention is made of either country. Strange to say the most perfect allegory in the English language was written by an almost illiterate and ignorant man, and written too, in a dungeon cell. In the "Pilgrim's Progress," Bunyan, the itinerant tinker, has given us by far the best allegory ever penned. Another good one is "The Faerie Queen" by Edmund Spenser.
Synecdoche (from the Greek, sun with, and ekdexesthai, to receive), is a figure of speech which expresses either more or less than it literally denotes. By it we give to an object a name which literally expresses something more or something less than we intend. Thus: we speak of the world when we mean only a very limited number of the people who compose the world: as, "The world treated him badly." Here we use the whole for a part. But the most common form of this figure is that in which a part is used for the whole; as, "I have twenty head of cattle," "One of his hands was assassinated," meaning one of his men. "Twenty sail came into the harbor," meaning twenty ships. "This is a fine marble," meaning a marble statue.
Metonymy (from the Greek meta, change, and onyma, a name) is the designation of an object by one of its accompaniments, in other words, it is a figure by which the name of one object is put for another when the two are so related that the mention of one readily suggests the other. Thus when we say of a drunkard—"He loves the bottle" we do not mean that he loves the glass receptacle, but the liquor that it is supposed to contain. Metonymy, generally speaking, has, three subdivisions: (1) when an effect is put for cause or vice versa: as "Gray hairs should be respected," meaning old age. "He writes a fine hand," that is, handwriting. (2) when the sign is put for the thing signified; as, "The pen is mightier than the sword," meaning literary power is superior to military force. (3) When the container is put for the thing contained; as "The House was called to order," meaning the members in the House.
Exclamation (from the Latin ex, out, and clamare, to cry), is a figure by which the speaker instead of stating a fact, simply utters an expression of surprise or emotion. For instance when he hears some harrowing tale of woe or misfortune instead of saying,—"It is a sad story" he exclaims "What a sad story!"