It will hardly be expected that we should arbitrate among these theories, inasmuch as our purpose is not to test the comparative truthfulness of metaphysical opinions, but to refer sceptical opinions in religion to their true scientific and metaphysical parentage. Truth is probably to be found in a selection from all; and historical investigation is the chief means of discovering the mode of conducting the process. It is at least certain, that if history be the form which science necessarily takes in the study of that which is subject to laws of life and organic growth, it must be the preliminary inquiry in any investigation in reference to mental phenomena. The history of philosophy must be the approach to philosophy.(109) The great problem of philosophy is method; and if there be a hope that the true method can ever be found it must be by uniting the historical analysis of the development of the universal mind with the psychological analysis of the individual. The history of thought indicates not only fact but truth; not only shows what has been, but, by exhibiting the proportions which different faculties contribute toward the construction of truth, and indicating tendencies as well as results, prepares materials to be collated with the decision previously made by mental and moral science concerning the question of what ought to be (9). A definite conviction on this metaphysical inquiry seems perhaps to be involved in the very idea of criticism, and necessary for drawing the moral from the history; yet the independence of our historical inquiry ought to be sacrificed as little as possible to illustrate a foregone conclusion. It will be more satisfactory to present the evidence for a verdict without undue advocacy of a side in the metaphysical controversy.(110) The execution of this design of analysing the intellectual causes of unbelief will necessarily involve to some extent a biographical treatment of the subject, both for theoretical and practical reasons, to discover truth and to derive instruction. This is so evident in the history of action, that there is a danger at the present time lest history should lose the general in the individual, and descend from the rank of science to mere biography.(111) The deeper insight which is gradually obtained into the complexity of nature, together with the fuller conviction of human freedom, is causing artistic portraiture and ethical analysis to be substituted for historical generalization. The same method however applies to the region of thought as well as will.