"Imagination, therefore, which transforms a visible object into an invisible image, fit to be stored in the mind, is the condition sine qua non for providing the mind with suitable thought-objects; but these thought-objects come into being only when the mind actively and deliberately remembers, recollects and selects from the storehouse of memory whatever arouses its interest sufficiently to induce concentration; in these operations the mind learns how to deal with things that are absent and prepares itself to ‘go further,’ toward the understanding of things that are always absent, that cannot be remembered because they were never present to sense experience."


Arendt, Hannah. The Life of the Mind (New York: Harcourt Brace & Company, 1978), I. p.76-77.