But whatever the importance of this nascent feeling, it was very far from sufficient to establish the conviction of Progress as a fundamental principle of human society. To demonstrate any kind of progression, at least three terms are requisite. Now the absolute character of theological philosophy, by which the comparison between Polytheism and Catholicism was instituted, prevented men from conceiving the bare possibility of any further stage. The limits of perfection were supposed to have been reached by the mediaeval system, and beyond it there was nothing but the Christian Utopia of a future life. The decline of mediaeval theology soon set the imagination free from any such obstacles; but it led at the same time to a mental reaction which for a long time was unfavourable to the development of this first conception of Progress. It brought a feeling of blind antipathy to the Middle Ages. Almost all thinkers in their dislike of the Catholic dogmas were seized with such irrational admiration for Antiquity as entirely to ignore the social superiority of the mediaeval system; and it was only among the untaught masses, especially in the countries preserved from Protestantism, that any real feeling of this superiority was retained. It was not till the middle of the seventeenth century that modern thinkers began to dwell on the conception of Progress. It re-appeared then under a new aspect. Conclusive evidence had by that time been furnished that the more civilized portion of our race had advanced in science and industry, and even, though not so unquestionably, in the fine arts. But these aspects were only partial: and though they were undoubtedly the source of the more systematic views held by our own century upon the subject, they were not enough to demonstrate the fact of a progression. And indeed, from the social point of view, so far more important than any other, Progress seemed more doubtful than it had been in the Middle Ages.