We return to Derrida's 1974 Glas. It has probably never occurred to readers of Glas that it could have relevance for any kind of critique of empire - let alone a critique of empire via the Mediterranean. But Braudel's investigation of the difficult question of the `historical Mediterranean' is precisely the lens through which Glas's nascent critique of imperialism comes into focus. In this strange work, a `thinking' of passages emerges - disruptive passages moving from west to east, ceaselessly criss-crossing the vectors of the western empire's seemingly `continuous' move westward. As a rigorous critique of origins and borders, Derridean deconstruction can provide a useful perspective on ongoing efforts to pinpoint the borders of a `historical Mediterranean' and on the ways in which medieval mercantile histories of the Mediterranean themselves serve as a critique of empire.