Theology in its normal sense is the science of God’s word. God’s word may be considered in the abstract as the revealed truth about God, in so far as this is expressible in human language. Alternatively it may be considered in the concrete as it lives and grows in individual human minds and hearts. Until the nineteenth century litde attempt had been made to describe and reflect upon the word of God in this latter sense. It would have been dismissed as unscientific. But scientific theology in its normal sense had existed for many centuries. The technical terms used in scientific theology were not, of course, revealed to us from heaven. Part of the achievement of the Christian theologian was to invent technical symbols to express what had been given to the Church untechnically in the inspired literature of the Scriptures and in the living tradition of the Church. Man’s capacity for scientific thought is one of his greatest gifts, and it was inevitable that he should apply it to the study of the greatest of all subjects, the revealed word of God. Christian man’s first attempts at theology came in the very beginnings of the patristic age. The need for clear-cut terms and arguments as a safeguard against heresy led to a great increase of theology during the golden age of patristics, the fourth and fifth centuries. But, contrasted with later theology, all this early period was a period of the literary expression of Christian life and tradition rather than of its systematic exposition and defence.