But the window operates by the continuous movement of an effusion which, ﬂowing from right to left, unites the attentive figures, the painter, and the canvas, with the spectacle they are observing; whereas the mirror, on the other hand, by means of a violent, instantaneous movement, a movement of pure surprise, leaps out from the picture in order to reach that which is observed yet invisible in front of it, and then, at the far end of its fictitious depth, to render it visible yet indifferent to every gaze.