By what has been said, the reader will not understand me as denying the propriety of comparing our conclusions in mental science with the Bible. Though no system of mental philosophy is directly revealed in the Bible, some one system is therein pre-supposed, and assuming, as we do, that the Scriptures are a revelation from God, we must suppose that the system of mental science assumed in the sacred writings, is the true system. If we could find the system pre-supposed in the Bible, we should have an infallible standard by which to test the validity of any conclusions to which we have arrived, as the results of psychological investigation. It is therefore a very legitimate, interesting, and profitable inquiry--what is the system of mental science assumed as true in the Bible? We may very properly turn our attention to the solution of such a question. In doing this, however, two things should be kept distinctly in mind. 1. In such inquiries, we leave the domain of mental philosophy entirely, and enter that of theology. In the latter we are to be guided by principles entirely distinct from those demanded in the former. 2. In reasoning from the Bible to the system of mental philosophy pre-supposed in the Scriptures, we are in danger of assuming wrong data as the basis of our conclusions that is, we are in danger of drawing our inferences from those truths of Scripture which have no legitimate bearing upon the subject, and of overlooking those which do have such a bearing. While there are truths of inspiration from which we may properly reason to the theory of the Will, pre-supposed in the Bible, there are other truths from which we cannot legitimately thus reason. Now suppose that we have drawn our conclusions from truths of inspiration which have no legitimate bearing upon the subject, truths which, if we do reason from them in the case, will lead us to wrong conclusions; suppose that in the light of such conclusions we have explained the facts of consciousness, assuming that such must be their true character, else we deny the Bible. Shall we not then have almost inextricably lost ourselves in the labyrinth of error? The following principles may be laid down as universally binding, if we would reason correctly, as philosophers and theologians, on the subject under consideration. 1. In the domain of philosophy, we must confine ourselves strictly and exclusively to the laws of psychological investigation, without reference to any system of theology. 2. In the domain of theology, when we would reason from the truths of inspiration to the theory of the Will pre-supposed in the Bible, we should be exceedingly careful to reason from those truths only which have a direct and decisive bearing upon the subject, and not from those which have no such bearing. 3. We should carefully compare the conclusions to which we have arrived in each of these domains, assuming that if they do not harmonize, we have erred either as philosophers or theologians.