This view of the world taught by Aristotle and followed by Alexander is apparent in Aristotle's "Meteorologica", a treatise on earth sciences where he discusses the "length" and "width" of "the inhabited earth." However, Aristotle knew that the Earth is spherical and even provided observational proof of this fact. Aristotle's cosmological view was that the Earth is round but he prescribed to the notion of an "inhabited Earth," surrounded by the Ocean, and an "uninhabited Earth" (though exactly how much of this was understood by his student Alexander the Great is not known).