[W]hat profoundly fascinated Benjamin from the beginning was never an idea, it was always a phenomenon.
[…]
If, for example—and this would certainly be in the spirit of Benjamin’s thought—the abstract concept Vernunft (reason) is traced back to its origin in the verb vernehmen (to perceive, to hear), it may be thought a word from the sphere of the superstructure has been given back its sensual substructure, or, conversely, that a concept has been turned into a metaphor—provided that “metaphor” is understood in its original, nonallegorical sense of metapherein (to transfer). For metaphor establishes a connection which is sensually perceived in its immediacy and requires no interpretation, while an allegory always proceeds from an abstract notion and then invents something palpable to represent it almost at will. […] What is so hard to understand about Benjamin is that without being a poet he thought poetically and therefore was bound to regard the metaphor as the greatest gift of language. Linguistic “transference” enables us to give material form to the invisible—“A mighty fortress is our God”—and thus to render it capable of being experienced.
Hannah Arendt, introduction to Walter Benjamin, Illuminations: Essays and Reflections