Metaphors are used for stylistic effect. They are artistic tools to create images and notions that appeal to the readers' knowledge and ability to make associations between things or representations. Some metaphors are easy to understand, such as "You are my sunshine"; others are more difficult because the compared elements have almost no relation to each other, as in "Fading memories are footprints in the sand." Dead, mixed and extended metaphors are some of the universally recognized metaphors. Active, complex, compound and absolute metaphors have also been identified, among others, but have not been entirely accepted.
Dead metaphors are an important type of metaphors because, in time, they changed from figures of speech to idioms and expressions. Being frequently uttered, they have lost their imaginative force and slipped unawares into the common language. They are no longer perceived as metaphors; hence, the term "dead." A phrase like "Happiness is within his grasp" doesn't actually mean the physical act of "grasping" at happiness, but the ability of a person to achieve it. Another example is, "He broke into their conversation;" it renders the idea of someone interfering with other people's conversation. Other examples that became clichés are "I'm dead tired," "He's at the end of his rope" and "It is bone-chilling cold."
Extended metaphors are another important type because they are largely used in literature. They consist of a main subject of a comparison and one or more secondary subjects that have some relation with the main one. They extend on more than one sentence and they can take the form of a phrase, a poem or an entire novel. A well-known example comes from the play "As You Like It" by William Shakespeare. Jacques' entire speech beginning with "All the world's a stage, and all the men and women merely players" is an extended metaphor. It describes life as a play in which the world is a theater stage and people are the actors playing their parts.
The poem "The Mouse Whose Name Is Time" by Robert Francis is another example of extended metaphor. It associates the abstract notion of time with the concrete image of a small animal whose main characteristic is that it can move unseen and unheard. "The mouse whose name is Time/ Is out of sound and sight./ He nibbles at the day/ And nibbles at the night." An even more extended metaphor is the entire novel "Animal Farm," by George Orwell. It describes the society during the Russian Revolution in 1917. Readers can easily understand the social structure and the political atmosphere of the time through familiar characters placed in a familiar setting. Mr. Jones represents the corrupt authority, the pig Napoleon is the absolute leader, and the dogs represent the brutal force ready to annihilate whoever opposes the regime.