Spengler was also influenced by the universal and cyclical vision of world history proposed by the German historian Eduard Meyer. The belief in the progression of civilizations through an evolutionary process comparable with living beings can be traced back to classical antiquity, although it is difficult to assess the extent of the influence those thinkers had on Spengler: Cato the Elder, Cicero, Seneca, Florus, Ammianus Marcellinus, and later, Francis Bacon, who compared different empires with each other with the help of biological analogies.