The Story of Art, E.H. Gombrich pg 239

if we want to understand the way in which northern art developed, we must appreciate this infinite care and patience of Jan van Eyck. The southern artists of his generation; the Florentine masters of Brunelleschi’s circle, had developed a method by which, nature could be represented in a picture with almost scientific accuracy. They began with the framework of perspective lines, and they built up the human body through their knowledge of anatomy and of the laws of foreshortenning. Van Eyck took the opposite way. He achieved the illusion of nature by patiently adding detail till his whole picture became like a mirror of the visible world. The difference between northern and Italian art remained important for many years. It is a fair guess to say that any work which excels in the representation of the beautiful surface of things, of flowers, jewels or fabric, will be by a northern artist, most probably by an artist from the Netherlands; while a painting with bold outlines, clear perspective and a sure mastery of the beautiful human body, will be Italian. - The Story of Art, E.H. Gombrich pg 239

The Story of Art, E.H. Gombrich pg 229

Brunelleschi was not only the initiator of Renaissance architecture. To him, it seems, is due another momentous discovery in the field of art, which also dominated the art of subsequent centuries - that of perspective. We have seen that even the Greeks, who understood foreshadowing, and the Hellenistic painters, who were skilled in creating the illusion of depth, did not know the mathematical laws by which objects appear to diminish in size as they recede from us. We remember that no artist could have drawn the famous avenue of trees leading back into the picture until it vanishes into the horizon. It was Brunelleschi who gave artists mathematical means of solving this problem; and the excitement which this caused among his painter-friends must have been immense. -