Before "cogito ergo sum" was ever conceived, Descartes introduced a number of enthymemic principles. The first was that he, as an individual, had the right to assert his wishes. The concept that the mere state of being a living, breathing human implies right and privileges is fundamental to most present-day beliefs, but at the time it was worse than disgusting; it was blasphemous.

Another example was his unshakeable self-confidence. Despite signs of anti-sociality, such as moving from house to house yearly without notice and keeping strange hours, Descartes was not intimidated by his separation from society, but rather insistent on it. It allowed him to...

At the age of twenty-three, he related that "those long chains of reasons...had caused me to imagine that all things which fall under the cognizance of man might very likely by related in the same fashion" [emphasis added] (Lo Bello 5). This view, arrogant thought it may have been, preserved his sanctity of though for an entire lifetime.
Which, as it turns out, is precisely how long it takes to earn immortality.