The Association began to make use of colporters about the year 1847. The next year it had two young ministers engaged in this work, and by 1850 this kind of missionary labor had increased to considerable proportions. Especially in the West was much use made of the colporter, and in this way in many of the states the works of Channing were sold in large numbers. By these agents, tracts were given away with a free hand, and books were given to ministers and those who especially needed them. The Western ministers, almost without exception, served as colporters, selling books and distributing them as important helps to their missionary labors. In many communities zealous laymen took part in this kind of service, and the several depositaries of books and tracts were used as centres from which colporters and others could draw their supplies. As early as 1835 a general depositary had been established in Cincinnati, and in 1849 one was opened in Chicago. The Association could not have undertaken any work that would have brought in a larger or more immediate return in the way of religious education and spiritual growth than this of the publication of tracts and books. Previous to 1850 a doctrinal sermon was rarely preached in a Unitarian church, and the tracts were the most important means of giving to the members of established churches a knowledge of Unitarian theology. By the same means many other persons were made acquainted with the Unitarian beliefs, and the result was to be seen in the formation of churches where tracts and books had been largely distributed.[14] [Sidenote: Domestic Missions.] The work of domestic missions from the first largely claimed the attention of the Association, and it was one the chief objects in its formation. During the summer of 1826 the members of the Harvard Divinity School were sent throughout New England to gather information, and to preach where opportunity offered. The special object was to make ministers and congregations acquainted with the purposes of the Association. It was found that there was much opposition to it, and that in many parishes there existed no desire to have its mission extended.