A now famous term used by T.S.Eliot in an essay ”On Hamlet“ (1919). The relevant passage is: ”The only way of expressing emotion in the form of art is by finding an objective correlative; in other words, a set of objects, a situation, a chain of events, which shall be the formula of that particular emotion; such that when the external facts, which must terminate in sensory experience are given the emotion is immediately evoked.

Eliot goes on to suggest in Lady Macbeth's sleep walking and in the speech that Macbeth makes when he hears of his wife death, the words are completely adequate to the state of mind; whereas in Hamlet the prince is ”dominated by a state of mind which is inexpressive, because it is in excess of the facts as they appear“. These observations have provoked a good deal of debate.

In other therms a successful artistic creation requires an exquisite balance between coalescence of form and matter. If the matter (thought, feeling, action) is ”too much“, ”in excess of “ the form (words) we have a discrepancy, strain, a lack of unity (that is insufficient correlation; they don't ”fadge“).

Vice versa, another kind of discrepancy and strain: the experience is overwhelmed by the words. Colloquially we say ”I was speechless“, ”it was indescribable“. In other words we have not found the ”formula“. In reverse, lacking the formula again we over describe, say too much.