Meanwhile in agriculture the Hollanders displayed a similar combination of scientific resourcefulness and indomitable energy. They discovered the value as fodder of certain “artificial” grasses and clovers, and experimented with these to the immense improvement of their cattle and dairy produce; and by the application of intensive methods to the cultivation of the land so increased its productivity, that it became capable of supporting three times the population which had before subsisted on it. Further, by promoting the cultivation of the potato and other root-vegetables they wrought a signal improvement in the public health, since the variety of diet, thus made possible in winter, stamped out the scurvy and leprosy which had been the scourge of Holland as of other countries. At the same time they developed their fisheries and introduced improved methods of drying and treating fish; enlarged their merchant marine, so that they became the chief carriers of the world; and pushed their commerce with the Indies, until they [Illustration: LANDSCAPE WITH FENCE JACOB VAN RUISDAEL IMPERIAL ACADEMY, VIENNA] possessed a practical monopoly of the most lucrative trade of those times, namely, that of spices. Meanwhile, as a reverse to this story of national progress, were the religious and political dissensions that crept into the commonwealth. Protestantism, after presenting a solid front to Romanism, now found itself cleft by the sect-rivalries of Arminians and Gomarists; and these in time gave color and opportunity to the ambition of Maurice. No disinterested patriot like his father, William the Silent, the second Stadtholder intrigued for his personal aggrandizement, and stained his memory by the judicial murder of the old patriot-statesman Barneveldt. On the other hand, of better memory was his service to art. In 1611 he commissioned Ravesteyn to paint a series of portraits of officers. These and other pictures that he gathered adorned his palace, and, added to by his successor, the Stadtholder Frederick Henry, became the nucleus of the collection that, accumulating through various vicissitudes, now occupies the Mauritshuis, as the Royal Museum of The Hague.