‘A small block of nervous tissue left from several days, hardening in Müller fluid alone or mixed with osmic acid. Because the histologist was distracted, or because of a scientist’s curiosity, it was immersed in a bath of silver nitrate. One sections the block, dehydrates the sections, clears them, and examines them. Surprising sight! Against a perfectly translucent, yellow background, appear, thinly dispersed, the black filaments, either smooth and delicate or spiny and thick; the black cell bodies, triangular, stellate, fusiform. They might be drawings done with India ink on transparent Japanese vellum. One is taken aback; the eye is accustomed to the inextricable tangles seen in sections stained with carmine or hematoxylin, where the mind strains in prodigies of criticism and interpretation, always in doubt. Here everything is simple, clear without confusion. Nothing more to interpret.