In spite of all this, and although the Renaissance is from some points of view a retrogression towards social conditions which had long disappeared, it was more than this; it was the awakening of the spirit of initiative; it was a forward impulse, a bold step in advance. It was not limited to a mere renewal of relations with classical antiquity; it stimulated inventive effort, and taught men to think for themselves once more, to open their eyes and to observe. It thus gave a strong impetus to science. The age is rich in many-sided geniuses and seekers after truth, who widened the field of human knowledge and power in every direction. It saw the birth of those universalists, Leonardo da Vinci and Michael Angelo, who may be likened to trees, which, by the mysterious process of grafting, bear twenty different kinds of fruit. In short, the Renaissance was a setting free of intelligence, a breaking forth of truths, which, thanks to printing, spread all over the world and became a lasting possession. It is true, indeed, that mankind, like the Wandering Jew, is always moving forward, and never comes completely to a standstill. Man moves ceaselessly because he is alive. But after the great creative movement which is the glory of modern times, his progress is more apparent, surer, and more rapid. From this time must be dated a permanent alliance between science and industry, exemplified in that heroic potter, Bernard Palissy, who spent his life and fortune in rediscovering the secret of certain enamelled pottery. The pity is that this alliance, so fruitful in new methods, in the exploitation of new materials and new products, was formed at the expense of the guilds; for the innovations which it rendered necessary were the death of their rules governing manufacture. Everything contributed, as we can see, to the break-up of the organization of labour which they embodied.