The Enchiridion by St. Augustine
Chapter 118.--The Four Stages of the Christian's Life, and the Four Corresponding Stages of the Church's History.
When, sunk in the darkest depths of ignorance, man lives according to the flesh undisturbed by any struggle of reason or conscience, this is his first state. Afterwards, when through the law has come the knowledge of sin, and the Spirit of God has not yet interposed His aid, man, striving to live according to the law, is thwarted in his efforts and falls into conscious sin, and so, being overcome of sin, becomes its slave (|for of whom a man is overcome, of the same is he brought in bondage| ); and thus the effect produced by the knowledge of the commandment is this, that sin worketh in man all manner of concupiscence, and he is involved in the additional guilt of willful transgression, and that is fulfilled which is written: |The, law entered that the offense might abound.| This is man's second state. But if God has regard to him, and inspires him with faith in God's help, and the Spirit of God begins to work in him, then the mightier power of love strives against the power of the flesh; and although there is still in the man's own nature a power that fights against him (for his disease is not completely cured), yet he lives the life of the just by faith, and lives in righteousness so far as he does not yield to evil lust, but conquers it by the love of holiness. This is the third state of a man of good hope; and he who by steadfast piety advances in this course, shall attain at last to peace, that peace which, after this life is over, shall be perfected in the repose of the spirit, and finally in the resurrection of the body. Of these four different stages the first is before the law, the second is under the law, the third is under grace, and the fourth is in full and perfect peace. Thus, too, has the history of God's people been ordered according to His pleasure who disposeth all things in number, and measure, and weight. For the church existed at first before the law; then under the law, which was given by Moses; then under grace, which was first made manifest in the coming of the Mediator. Not, indeed, that this grace was absent previously, but, in harmony with the arrangements of the time, it was veiled and hidden. For none, even of the just men of old, could find salvation apart from the faith of Christ; nor unless He had been known to them could their ministry have been used to convey prophecies concerning Him to us, some more plain, and some more obscure.