In all discussions concerning sin and grace, the question con- cerning the nature and necessary conditions of free agency is of necessity involved. This is one of the points in which theology and psychology come into immediate contact. There is a theory of free agency with which the doctrines of original sin and of effi- cacious grace are utterly irreconcilable, and there is another theory with wliich those docti'ines are perfectly consistent. In all ages of the Church, therefore, those who have adopted the former of these theories, reject those doctrines ; and, on the other hand, those who are constrained to believe those doctrines, are no less constrained to adopt the other and congenial theory of free agency. Pelagians, Semi-Pelagians, and Remonstrants are not more notoriously at va- riance with Augustinians, Lutherans, and Calvinists, on the doc- trines of sin and grace, than they are on the metaphysical and moral question of human liberty. In every system of theology, therefore, there is a chapter De libera arbitrio. This is a question which every theologian finds in his path, and which he must dis- pose of; and on the manner in which it is determined depends his theology, and of course his religion, so far as his theology is to him a truth and reality.
It may seem preposterous to attempt, in the compass of a few pages, the discussion of a question on which so many volumes have been written. There is, however, this important difference between all subjects which relate to the soul, or the world within, and those which relate to the external world : with regard to the former, all the materials of knowledge being facts of consciousness, are already in our possession ; whereas, in regard to the latter, the facts have first to be collected. In questions, therefore, which relate to the mind, a mere statement of the case is often all that is required, and all that can be given. If that statement be correct, the facts of consciousness spontaneously arrange themselves in order around it ; if it be incorrect, they obstinately refuse to be thus marshalled. If this be so, why is it that men differ so much about these questions ? To this it may be answered, —
1. That they do not differ so much as they appear to. When