Natural philosophy also, in the course of its search for truth, as it threw off both one-sided Christian ideas and ancient traditions, came gradually to feel an interest in Nature; not only her laws, but her beauty, became an object of enthusiastic study. By a very long process of development the Hellenic feeling for Nature was reached again in the Renaissance; but it always remained, despite its sentimental and pantheistic elements, sensual, superficial, and naive, in comparison with Christian feeling, which a warmer heart and a mind trained in scholastic wisdom had rendered more profound and abstract. Hence Nature was sometimes an object of attention in detail, sometimes in mass.[2] As we come to the first landscape painters and their birthplace in the Netherlands, we see how steady and orderly is the development of the human mind, and how factors that seem isolated are really links in one chain. In the Middle Ages, landscape was only background with more or less fitness to the subject. By the fifteenth century it was richer in detail, as we see in Pisanello and the Florentines Gozzoli and Mantegna. The poetry of earth had been discovered; the gold grounds gave way to field, wood, hill, and dale, and the blue behind the heads became a dome of sky. In the sixteenth century, Giorgione shewed the value of effects of light, and Correggio's backgrounds were in harmony with his tender, cheerful scenes. Titian loved to paint autumn; the sunny days of October with blue grapes, golden oranges, and melons; and evening with deep harmonies of colour over the sleeping earth. He was a great pioneer in the realm of landscape. With Michael Angelo not a blade of grass grew; his problem was man alone. Raphael's backgrounds, on the other hand, are life-like in detail: his little birds could fly out of the picture, the stems of his plants seem to curve and bend towards us, and we look deep into the flower they hold out.[3] In the German Renaissance too, the great masters limited themselves to charming framework and ingenious arabesques for their Madonnas and Holy Families. But, as Lübke says,[4] one soon sees that Dürer depended on architecture for borders and backgrounds far less than Holbein; he preferred landscape. 'The charm of this background is so great, the inwardness of German feeling for Nature so strongly expressed in it, that it has a special value of its own, and the master through it has become the father of landscape painting.'[5]