The world as Aristotle and his contemporaries saw it was already a spent world. Its original creativeness had flowered during the sixth and fifth centuries in an outburst of discovery and invention in political and social as well as in literary fields. By the middle of the fourth century, it was the turn of the philosopher to take the results of the discoveries, and synthesize and publicize them in such a way that all the Greek communities should be enabled to work out the combination of forms of society and government best suited to their needs. The study made by Aristotle of the states of his own day maintained its authority across empire and into nationalism, through antiquity and the Middle Ages, up to the threshold of our own modern capitalistic civilization. From that time, however, a new era of inventions seems to have erected an insurmountable barrier between the old and the new, and the relevance of earlier thought for modern problems is called in question.