Philosophers of perception and psychologists first studied ‘multistable’ or ‘reversible’ figures, Kippbilder, in the nineteenth century. The earliest description of the phenomenon of a ‘sudden and involuntary change in the apparent position’ of a represented object occurred in a letter written by Louis Albert Necker in Geneva to Sir David Brewster on 24 May 1832 and published six months later in the Philosophical Magazine. The picture in question would become known as the Necker cube.