In 1220 form one of the most momentous epochs in Innocent Italian history.
This was one of the few great epochs of geographical discovery.
It was the great work of Descartes to exclude rigorously from science all explanations which were not scientifically verifiable; and the prevalence of materialism at certain epochs, as in the enlightenment of the 18th century and in the German philosophy of the middle, 9th, were occasioned by special need to vindicate the scientific position, in the former case against the Church, in the latter case against the pseudo-science of the Hegelian dialectic. The chief definite periods of materialism are the pre-Socratic and the post-Aristotelian in Greece, the 18th century in France, and in Germany the, 9th century from about 1850 to 1880.
The keel has been lost, and is being lost, at various epochs and by various groups of birds.
It should be observed that the tyranny of Peisistratus is one of the many epochs of Greek history on which opinion has almost entirely changed since the age of Grote.