The Bedford Glossary of Critical and Literary Terms - Ross Murfin 2018
Tension: (1) Generally, the balance or equilibrium between opposing elements in a literary work, especially a poem, that give it stability and wholeness. (2) As used by New Critic Allen Tate in “Tension in Poetry” (1938), the totality of, or interrelation between, what he defined as the two types of meaning in a poem: “extension” (concrete, denotative meaning) and “intension” (abstract, metaphorical meaning). Tate deemed tension the “central achievement in poetry,” arguing that “good poetry is a unity of all the meanings from the furthest extremes of intension and extension.” Examining the use of gold as an image in John Donne’s “A Valediction: Forbidding Mourning” (1640), for instance, Tate argued that while the denotative conception of gold as finite logically contradicts its connotation of infinity, the two meanings enrich rather than invalidate one another.
In a distinct but related usage, New Critics as well as other types of critics applied the term tension to “conflict structures,” that is, binary oppositions, or contrary pairs of qualities, such as abstract / concrete, general / particular, and structure / texture. New Critics in particular tended to evaluate poems in part based on the manifestation of such oppositions, especially insofar as they involved irony and paradox. Some critics maintained that the tension itself gives a work its form and even its cohesiveness.