On The Holy Trinity by St. Augustine
Chapter 18.--The Son of God Became Incarnate in Order that We Being Cleansed by Faith May Be Raised to the Unchangeable Truth.
24. Since, then, we were not fit to take hold of things eternal, and since the foulness of sins weighed us down, which we had contracted by the love of temporal things, and which were implanted in us as it were naturally, from the root of mortality, it was needful that we should be cleansed. But cleansed we could not be, so as to be tempered together with things eternal, except it were through things temporal, wherewith we were already tempered together and held fast. For health is at the opposite extreme from disease; but the intermediate process of healing does not lead us to perfect health, unless it has some congruity with the disease. Things temporal that are useless merely deceive the sick; things temporal that are useful take up those that need healing, and pass them on healed, to things eternal. And the rational mind, as when cleansed it owes contemplation to things eternal; so, when needing cleansing, owes faith to things temporal. One even of those who were formerly esteemed wise men among the Greeks has said, The truth stands to faith in the same relation in which eternity stands to that which has a beginning. And he is no doubt right in saying so. For what we call temporal, he describes as having had a beginning. And we also ourselves come under this kind, not only in respect to the body, but also in respect to the changeableness of the soul. For that is not properly called eternal which undergoes any degree of change. Therefore, in so far as we are changeable, in so far we stand apart from eternity. But life eternal is promised to us through the truth, from the clear knowledge of which, again, our faith stands as far apart as mortality does from eternity. We then now put faith in things done in time on our account, and by that faith itself we are cleansed; in order that when we have come to sight, as truth follows faith, so eternity may follow upon mortality. And therefore, since our faith will become truth, when we have attained to that which is promised to us who believe: and that which is promised us is eternal life; and the Truth (not that which shall come to be according as our faith shall be, but that truth which is always, because in it is eternity, -- the Truth then) has said, |And this is life eternal, that they might know Thee the only true God, and Jesus Christ, whom Thou hast sent:| when our faith by seeing shall come to be truth, then eternity shall possess our now changed mortality. And until this shall take place, and in order that it may take place, -- because we adapt the faith of belief to things which have a beginning, as in things eternal we hope for the truth of contemplation, lest the faith of mortal life should be at discord with the truth of eternal life, -- the Truth itself, co-eternal with the Father, took a beginning from earth, when the Son of God so came as to become the Son of man, and to take to Himself our faith, that He might thereby lead us on to His own truth, who so undertook our mortality, as not to lose His own eternity. For truth stands to faith in the relation in which eternity stands to that which has a beginning. Therefore, we must needs so be cleansed, that we may come to have such a beginning as remains eternal, that we may not have one beginning in faith, and another in truth. Neither could we pass to things eternal from the condition of having a beginning, unless we were transferred, by union of the eternal to ourselves through our own beginning, to His own eternity. Therefore our faith has, in some measure, now followed thither, whither He in whom we have believed has ascended; born, dead, risen again, taken up. Of these four things, we knew the first two in ourselves. For we know that men both have a beginning and die. But the remaining two, that is, to be raised, and to be taken up, we rightly hope will be in us, because we have believed them done in Him. Since, therefore, in Him that, too, which had a beginning has passed over to eternity, in ourselves also it will so pass over, when faith shall have arrived at truth. For to those who thus believe, in order that they might remain in the word of faith, and being thence led on to the truth, and through that to eternity, might be freed from death, He speaks thus: |If ye continue in my word, then are ye my disciples indeed.| And as though they would ask, With what fruit? He proceeds to say, |And ye shall know the truth.| And again, as though they would say, Of what good is truth to mortal men? |And the truth,| He says, |shall make you free.| From what, except from death, from corruptions, from changeableness? Since truth remains immortal, incorrupt, unchangeable. But true immortality, true incorruptibility, true unchangeableness, is eternity itself.