  After suppressing his World, Descartes decided to put forward, anonymously, a limited sample of his new philosophy, in the Discourse with its attached essays. The Discourse recounted Descartes' own life journey,  explaining how he had come to the position of doubting his previous knowledge and seeking to begin afresh. It offered some initial results of his metaphysical investigations, including mind–body dualism. It did not, however, engage in the deep skepticism of the later Meditations, nor did it claim to establish, metaphysically, that the essence of matter is extension. This last conclusion was presented merely as a hypothesis whose fruitfulness could be tested and proven by way of its results, as contained in the attached essays on Dioptrics and Meteorology. The latter subject area comprised “atmospheric” phenomena. In his Meteorology, Descartes described his general hypothesis about the nature of matter, before continuing on to provide accounts of vapors, salt, winds, clouds, snow, rain, hail, lightning, the rainbow, coronas, and parhelia.