“Tain (tēin), sb. [a.F. tain tinfoil altered from F. étain, tin…].
Oxford English Dictionary
The breakthrough toward radical otherness (with respect to the philosophical concept – of the concept) always takes within philosophy, the form of an aposteriority or an empiricism. But this is an effect of the specular nature of philosophical reflection, philosophy being incapable of inscribing (comprehending) what is outside it otherwise than through the appropriating assimilation of a negative image of it, and dissemination is written on the back-the tain-of that mirror.
Jacques Derrida, Dissemination”
(Epigraph to “The Tain of the Mirror: Derrida and the Philosophy of Reflection “, Rodolphe Gasché: (1986))