The fourth of the governing motives of imperial expansion is the need of finding new homes for the surplus population of the colonising people. This was not in any country a very powerful motive until the nineteenth century, for over-population did not exist in any serious degree in any of the European states until that age. Many of the political writers in seventeenth-century England, indeed, regarded the whole movement of colonisation with alarm, because it seemed to be drawing off men who could not be spared. But if the population was nowhere excessive, there were in all countries certain classes for which emigration to new lands offered a desired opportunity. There were the men bitten with the spirit of adventure, to whom the work of the pioneer presented an irresistible attraction. Such men are always numerous in virile communities, and when in any society their numbers begin to diminish, its decay is at hand. The imperial activities of the modern age have more than anything else kept the breed alive in all European countries, and above all in Britain. To this type belonged the conquistadores of Spain, the Elizabethan seamen, the French explorers of North America, the daring Dutch navigators. Again, there were the younger sons of good family for whom the homeland presented small opportunities, but who found in colonial settlements the chance of creating estates like those of their fathers at home, and carried out with them bands of followers drawn from among the sons of their fathers' tenantry. To this class belonged most of the planter-settlers of Virginia, the seigneurs of French Canada, the lords of the great Portuguese feudal holdings in Brazil, and the dominant class in all the Spanish colonies. Again, there were the 'undesirables' of whom the home government wanted to be rid--convicts, paupers, political prisoners; they were drafted out in great numbers to the new lands, often as indentured servants, to endure servitude for a period of years and then to be merged in the colonial population. When the loss of the American colonies deprived Britain of her dumping-ground for convicts, she had to find a new region in which to dispose of them; and this led to the first settlement of Australia, six years after the establishment of American independence. Finally, in the age of bitter religious controversy there was a constant stream of religious exiles seeking new homes in which they could freely follow their own forms of worship. The Puritan settlers of New England are the outstanding example of this type. But they were only one group among many. Huguenots from France, Moravians from Austria, persecuted 'Palatines' and Salzburgers from Germany, poured forth in an almost unbroken stream. It was natural that they should take refuge in the only lands where full religious freedom was offered to them; and these were especially some of the British settlements in America, and the Dutch colony at the Cape of Good Hope.