The development of manufactures naturally brought about changes in the organisation of industry. Owing to the operation of the principle of division of labour, new crafts came into existence, and these, in their turn, were also sub-divided into other new crafts. Gradually, all the various classes of the industrial world--the artisan, the manufacturer, the middleman, and the merchant--began to emerge. As a result, the "rude beginnings of a factory system" manifested themselves,[382] and there are even traces of a movement which resembles a modern strike.[383] These changes in the industrial system necessarily exerted a powerful influence upon the agricultural industry, which previously had been the principal occupation of the people. The Black Death had been responsible for a great diminution in the number of agricultural labourers, and as a result, it was scarcely possible to find sufficient labour for the cultivation of the soil. This scarcity of labour was intensified by the fact that employment in the manufacturing industries proved to many a more attractive form of occupation than service on the land. The Central Government took steps with the object of compelling people to work on the land, and an attempt was even made, as we shall see in a subsequent chapter, to prevent agricultural labourers from sending their children to school. Thus in the reign of Richard II., it was enacted that any person who was engaged on agricultural labour up to twelve years of age, was to be compelled to remain at that occupation during the remainder of his life.[384] Other Acts of Parliament, with a similar object, were passed in 1406 and 1444.[385] This repressive legislation failed to secure its purpose, as the steady flow of labour from agriculture to manufacture continued. The increasing scarcity of labour led naturally to the gradual substitution of sheep farming for the cultivation of wheat, a development to which the growth of the cloth industry necessarily contributed. The demand for wool by the English manufacturers of cloth increased to so great an extent that sheep-farming gradually became more profitable than the cultivation of the soil and, as a result, the enclosure movement, which began to set in during the closing years of the fourteenth century, made such progress that, during the fifteenth century, there occurred "the greatest of those agricultural changes which have in successive ages swept over this country--the transition from arable to pasture farming."[386]