old charts which the astrologers made and compare them with the charts of astronomers of our day.  How vast the difference!  Listen to our astronomers talk about the magnitudes and disunites and composition of the stars, and compare with their story that which was written in the astronomy of a few centuries ago.  The stellar universe has not changed, but men’s conceptions have changed amazingly.  The facts of the human body do not change.  Our heart beats as the heart of Homer beat, our blood flows as the blood of Julius Caesar flowed, our muscles and nerves live and die as the nerves and muscles have lived and died in the bodies of men in all the generations—­and yet, how the theories of medicine have been altered from time to time.  A doctor does not want to hear a medical lecturer speak who persists in using the phraseology and conceptions which were accepted by the medical science of fifty years ago.  Conceptions become too narrow to fit the growing mind of the world, and when once outgrown they must be thrown aside.  As it is in science, so it is in religion.  The facts of Christianity never change, they are fixt stars in the firmament of moral truth.  Forever and forever it will be true that Christ died for our sins, but the interpretations of this fact must be determined by the intelligence of the age.  Men will never be content with simple facts, they must go behind them to find out an explanation of them.  Man is a rational being, he must think, he will not sit down calmly in front of a fact and be content with looking it in the face, he will go behind it and ask how came it to be and what are its relations to other facts.  That is what man has always been doing with the facts of the Christian revelation, he has been going behind them and bringing out interpretations which will account for them.  The interpretations are good for a little while, and then they are outgrown and cast aside.

A good illustration of the progressive nature of theology is found in the doctrine of the atonement.  All of the apostles taught distinctly that Christ died for our sins.  The early Christians did not attempt to go behind that fact, but by and by men began to attempt explanations.  In the second century a man by the name of Irenaeus seized upon the word “ransom” in the sentence, “The Son of man is come to give his life a ransom for many,” and found in that word “ransom” the key-word of the whole problem.  The explanation of Irenaeus was taken up in the third century by a distinguished preacher, Origen.  And in the fourth century the teaching of Origen was elaborated by Gregory of Nyssa.

According to the interpretation of these men, Jesus was the price paid for the redemption of men.  Paul frequently used the word redemption, and the word had definite meanings to people who lived in the first four centuries of the Christian era.  If Christ was indeed a ransom, the question naturally arose, who paid the price?  The answer was, God.  A ransom must be paid to somebody—­to whom