Man clings to life in spite of all its evils. This shows that there is a reality for the soul. The material world may pass away, but the reality of soul-life is assured. Man’s inner life is ever present and cannot be imaginary. The fact that there is such a thing as probability implies the existence of certainty. Where shall I look for certainty? In myself. Certainty is there as a fact of inner observation. There are my inner mental states――my sensations, feelings, etc., whose existence cannot be doubted even if the existence of the objects to which they correspond is doubted. I am certain also of my own consciousness at that moment. To doubt my existence is to assert my existence. To doubt also implies that I will remember, live――for doubt rests upon these former ideas. The temporary character of the material world only strengthens the reality of this inner world. The existence of the material world cannot be demonstrated, and so man is driven inward to find a basis for its reality. Thus by a deep insight, although without much logical reasoning, Augustine transcends Aristotle, and anticipates modern thought by finding reality in the _unitary personality_, whose existence is an inner certainty. But Augustine is driven farther inward; for the certainty of the existence of God is involved in this inner certainty. My doubt about the character of the world of material things implies that their truth exists and that I have the capacity for measuring it. Such truths are universal. They transcend the individual consciousness, and their mutual agreement unites all rational beings in a common standard. On the other hand, this unity of truths implies the existence of God. Truths are the Ideas (Platonic) in God’s mind.[52] Full knowledge of God is denied to man in this life, but, nevertheless, all morality consists in love for God; all science is only an interest in the working of God in nature; all the beauty in the world around us points to the harmonious ordering of God; the history of the world is only the free act of God. Thus, in brief, does Augustine centralize the principle of inner spirituality――of “internality.” Thus does he put into control the certainty of consciousness.