In the late eighties, Polke began to take an increasing interest in random incidents, the chemical freedom of materials which, given their extreme dissimilarity and the variety of their roots—synthetic resins, mineral pigments, lacquers, tellurium, etc.—produce unexpected internal reactions and external effects which generate ambiguous, veiled, almost secret images, on which both artist and spectator have to superimpose a final narrative or literary meaning deriving from their very material nature. In 1986, for example, his contribution to the German pavilion at the Venice Biennale, the piece entitled Athanor, reacted to the humidity, not only changing its colour—from a diluted blue to a pinkish violet—but also revealing or concealing the figures that composed it. "For me the important thing is the chemical process of the picture," he wrote, "the alchemy of colour. There are fish, like the flounder, that adapt their colour to the environment like chameleons. But we cannot do that, we have to use the alchemy of colour, such as the effect of radio waves on a transparency or of a shine on the picture which, on a first impression, we are unable to locate, but which, nevertheless, send an image to our retina which awakens a yearning for the unknown in us." The list of his experiments is endless and also includes visual essays with photocopies, reproducible material, etc. And he also used poisons; according to a statement of his which, in a way, aptly depicts him, "Poison produces a very definite effect. Art produces none." In Mephisto, whose most recognisable image is that of footprints in the lower part of the canvas, in addition to the use of mixed media there is another outstanding feature which has been one of his significant routines: the grid, here ironically reduced to a globular system that seems to disappear beneath the albino blaze in the centre right of the picture. A recent portrait of Polke has been entitled The Beauty of the Devil and, as Kevin Power has rightly said, "There is a whole Avernus around Polke's imagination which his work conveys to us, although it can never materialise or fully take shape." The three large panels that make up Triptyque, with their random mixtures of paint and lacquer, remind me of other very similar works, but from earlier periods, such as The Instructor and Das war schon immer so, from 1982. However, this work was painted at the same time as one of his most political series, which he dedicated to the French Revolution.