METAPHOR

Metaphor by etymology came from Greek meta (μετά) “between” and phero (φέρω), “to bear”, “to carry” that combine to be metaphero (μεταφέρω) that mean “transfer” or “carry over”. Metaphor is a figure of speech concisely comparing two things, saying that one is the other (http://www.wikipedia/metaphor.html).
In Diksi dan Gaya Bahasa, Gorys Keraf said that “metafora adalah semacam analogi yang membandingkan dua hal secara langsung, tetapi dalam bentuk singkat” (2002:139). It means implied comparison between two usually unrelated things indicating a likeness or analogy between attributes found in both things.
Metaphor is in two parts: the tenor and the vehicle. The tenor is the subject to which attributes are ascribed. The vehicle is the subject whose attributes are borrowed.
For example: “No more for him life’s stormy conflicts”, (second stanza, line one in Hush’d Be the Champ’s To-Day).

Stormy conflicts, it means the conflicts are horrible like storm. Civil War and slavery are the horrible is the conflicts in United States of America. Describing the attribute of “conflicts” is a tenor and “stormy” is a vehicle.

Metaphor is present in the oldest written Sumerian language narrative, the Epic of Gilgamesh. The Greek plays of Sophocles, Aeschylus, and Euripides, among others, were almost invariably allegorical, showing the tragedy of the protagonists, either to caution the audience metaphorically about temptation, or to lambast famous individuals of the day by inferring similarities with the caricatures in the play. Now we can see that any theme in literature is a metaphor, using the story to convey information about human perception of the theme in question. (http://www. wikipedia.com/metaphor.html).
Metaphor have several types, there are metonymy, simile, synecdoche, catachresis, parable, fable, and allegory.

Simile
Simile is a figure of speech comparing two unlike things, often introduced with the word "like" or "as".
For example: “Charging like ceaseless clouds across the sky” (Hush’d Be The Champ’s To-Day, 3rd line, 2nd stanza).

Synecdoche
Synecdoche is a figure of speech in which a term denoting a part of something is used to refer to the whole thing (Pars pro toto), or a term denoting a thing (a "whole") is used to refer to part of it (Totum pro parte), or a term denoting a specific class of thing is used to refer to a larger, more general class, or a term denoting a general class of thing is used to refer to a smaller, more specific class (Bindo pro parte), or a term denoting a material is used to refer to an object composed of that material.
For example: “O Captain! my Captain!” (O Captain! my Captain! 1st line 1st and 2nd stanza). It refers to Abraham Lincoln.

Allegory
Allegory is the intentional conveying, by means of symbol and image, of a further, deeper meaning than the surface one. Allegory may thus be said to be extended metaphor, worked out in many relationship. It is of greater length and complexity than parable or fable and is imaginative where analogy is rational (Benton, 1968: 641).
For example is the poem entitled Reversals. It is about changing of social condition in United States of America after the Civil War end and proclaimed Declaration of Emancipation.