What is it about?
Equivalence has proved the most elusive concept in translationa... for good reason, since, as I posit, it is not the condition but the consequence of translating as the crucial, but by far not the only, form of interlingual mediation, alway post facto, ever different.
Why is it important?
To my mind, it stands translation on its feet, as, as it were, the zero degree of intelingual mediaiton, whose aim it is: on the basis of what the original says, to say what it is necessary or convenient so that the new interlocutor understand what it is necessary or convenient that he understand, the way it is necessary or convenient that he understand it in view of the metalinguistic purposes of the mediator´s utterance (which is normally imposed upon him or conditioned by the client´s brief).