Human liberty is an assured fact; we are free to do good or evil. But then God has not been able to know in advance what I shall do to-day, and in consequence God, at least in His knowledge, has limitations, is not omnipotent. St. Augustine replies confusedly (for the question is undoubtedly insoluble) that we have an illusion of liberty, an illusion that we are free, which suffices for us to acquire merit if we do right and demerit if we do wrong, and that this illusion of liberty is a relative liberty, which leaves the prescience of God, and therefore His omnipotence, absolute. Man is also extremely weak, debilitated, and incapable of good on account of original sin, the sin of our first parents, which is transmitted to us through heredity and paralyses us. But God helps us, and this is what is termed grace. He helps us gratuitously, as is indicated by the word "grace"--if He wishes and when He wishes and in the measure that He wishes. From this arises the doctrine of "predestination," by which it is preordained whether a man is to be saved or lost. PART II IN THE MIDDLE AGES CHAPTER I FROM THE FIFTH CENTURY TO THE THIRTEENTH Philosophy is only an Interpreter of Dogma. When it is Declared Contrary to Dogma by the Authority of Religion, it is a Heresy. Orthodox and Heterodox Interpretations. Some Independent Philosophers. DOGMA.--After the invasion of the barbarians, philosophy, like literature, sought refuge in monasteries and in the schools which prelates instituted and maintained near them. But the Church does not permit the free search for truth. The truth has been established by the Fathers of the Church and fixed by the Councils. Thenceforth the philosophic life, so to speak, which had never been interrupted, assumed a fresh character. Within the Church it sheltered--I will not say disguised--itself under the interpretation of dogma; it became a sort of respectful auxiliary of theology, and was accordingly called the "handmaid of theology," _ancilla theologiae_. When emancipated, when departing from dogma, it is a "heresy," and all the great heresies are nothing else than schools of philosophy, which is why heresies must come into a history of philosophy. And at last, but only towards the close of the Middle Ages, lay thought without disturbing itself about dogma and no longer thinking about its interpretation, created philosophic doctrines exactly as the philosophers of antiquity invented them apart from religion, to which they were either hostile or indifferent.