the positive establishment of certain truths of its own, without having for its vocation to challenge and put right the fundamental verdicts of man's natural judgment, the study of it might, not unreasonably, be declined on the ground that, by the exercise of our ordinary faculties, we were already in possession of as much truth as we wanted, or as was good for us. If truth comes to us spontaneously, why should we not be satisfied with it; why should we fatigue ourselves in the pursuit of any other truth than that which comes to us from nature? Why, indeed? But what if no truth, what if nothing but error comes to us from nature; what if the ordinary operation of our faculties involves us in interminable contradictions, and lands us in atheism at last? In that case, it is conceived that the usefulness of philosophy, as corrective of these spontaneous fallacies, and as emendatory of the inherent infirmities of the human intellect, cannot be too highly estimated, or its study too earnestly recommended.
As a discipline of necessary and demonstrated truth.30. Its importance is greatly enhanced by the consideration that, when rightly cultivated, it deals only with necessary and demonstrated truths. Its conclusions are not optional opinions to be embraced or not as people please: they are insuperable necessities of thinking, to understand which is to assent to them. Truth grounded on mere pro-