structural:expansion, linguistic:paraphrasing
Purported Rosicrucianism

The membership of Descartes to the Rosicrucians is debated.

The initials of his name have been linked to the R.C. acronym widely used by Rosicrucians. Furthermore, in 1619 Descartes moved to Ulm which was a well renowned international center of the Rosicrucian movement. During his journey in Germany, he met Johannes Faulhaber who had previously expressed his personal commitment to join the brotherhood.

Descartes dedicated the work titled The Mathematical Treasure Trove of Polybius, Citizen of the World to "learned men throughout the worldand especially to the distinguished B.R.C. (Brothers of the Rosy Cross) in Germany". The work was not completed and its publication is uncertain.