 Upon arriving in the Netherlands, Descartes undertook work on two sorts of topics. In Summer, 1629, an impressive set of parhelia, or false suns, were observed near Rome. When Descartes heard of them, he set out to find an explanation. (He ultimately hypothesized that a large, solid ice-ring in the sky acts as a lens to form multiple images of the sun [6:355].) This work interrupted his investigations on another topic, which had engaged him for his first nine months in the Netherlands (1:44)—the topic of metaphysics, that is, the theory of the first principles of everything that there is. The metaphysical objects of investigation included the existence and nature of God and the soul (1:144, 182). However, these metaphysical investigations were not entirely divorced from problems such as the parhelia, for he claimed that through his investigations into God and the human self, he had been able “to discover the foundation of physics” (1:144). Subsequently, Descartes mentioned a little metaphysical treatise in Latin—presumably an early version of the Meditations—that he wrote upon first coming to the Netherlands (1:184, 350). And we know that Descartes later confided to Mersenne that the Meditations contained “all the principles of my physics” (3:233).