Metaphor

As an expression in language, a metaphor describes one entity &mdash; e.g., object, event, thought, concept, activity, attribute &mdash; to imply comparison with another without the help of transitional words to indicate the act of comparison (such as "like" or "as" used in simile), relying instead on specific imagery and description to provide context for inferring the target of comparison.

Metaphor as style in speech and writing
Viewed as an aspect of speech and writing, metaphor qualifies as style, in particular, style characterized by a type of analogy. An expression (word, phrase) that by implication suggests the likeness of one entity to another entity gives style to an item of speech or writing, whether the entities consist of objects, events, ideas, activities, attributes, or almost anything expressible in language. For example, in the first sentence of this paragraph, the word ´viewed´ serves as a metaphor for ´thought of´, implying analogy of the process of seeing and the thought process. The phrase, "viewed as an aspect of", projects the properties of seeing (vision) something from a particular perspective onto thinking about something from a particular perspective, that ´something´ in this case referring to ´metaphor´ and that ´perspective´ in this case referring to the characteristics of speech and writing.

As a characteristic of speech and writing, metaphors can serve the poetic imagination, enabling William Shakespeare, in his play "As You Like It", to compare the world to a stage and its human inhabitants players entering and exiting upon that stage; enabling Sylvia Plath, in her poem "Cut", to compare the blood issuing from her cut thumb to the running of a million soldiers, "redcoats, every one"; and, enabling Robert Frost, in "The Road Not Taken", to compare one´s life to a journey.

Viewed also as an aspect of speech and writing, metaphor can serve as a device for persuading the listener or reader of the speaker-writer´s argument or thesis, the so-called rhetorical metaphor....

Metaphor as foundational to our conceptual system
Cognitive linguists emphasize that metaphors serve to facilitate the understanding of one conceptual domain, typically an abstract one like 'life' or 'theories' or 'ideas', through expressions that relate to another, more familiar conceptual domain, typically a more concrete one like 'journey' or 'buildings' or 'food'. Food for thought: we devour an article of raw facts, try to digest them, stew over them, let them simmer on the back-burner, regurgitate them in discussions, cook up explanations, hoping they do not seem half-baked. Theories as buildings: we establish a foundation for them, a framework, support them with strong arguments, buttressing them with facts, hoping they will stand. Life as journey: some of us travel hopefully, others seem to have no direction, many lose their way.

 A convenient short-hand way of capturing this view of metaphor is the following: CONCEPTUAL DOMAIN (A) IS CONCEPTUAL DOMAIN (B), which is what is called a conceptual metaphor. A conceptual metaphor consists of two conceptual domains, in which one domain is understood in terms of another. A conceptual domain is any coherent organization of experience. Thus, for example, we have coherently organized knowledge about journeys that we rely on in understanding life.