What was that man thinking?

Thomas Jefferson devised a layout of 10 new states from the Northwest Territory:

The names suggested for these ten States are a peculiar mixture of Latin and Indian, and while a semblance of some of the names still remains in two cases, in all others it is so absolutely forgotten that the very fact has ceased to be known by many close students of American history. Yet, besides this humane and noble piece of statesmanship (the proposed prohibition of slavery in the territory) we have a glimpse of that absurd element in Jefferson’s mind which his admirers sought to excuse by calling him a ‘philosopher’. The matter is small, to be sure, but suggestive. He proposed as names for the several subdivisions of this territory: Sylvania, Michigania, Cheronesus, Assenisippis, Metropotamia, Illinoia, Saratoga, Washington, Polypotamia, and Pelipsia.