And when Abram was ninety years old and nine, the LORD appeared to Abram, and said unto him,
I am the Almighty God; walk before me, and be you perfect.
Read Chapter 17
Ambrose of Milan
The words “be blameless” are addressed to Abraham, to whom had been given the spirit of wisdom, holy, marvelously agile, unpolluted. The soul of the just man, therefore, must be in training night and day, ever on the lookout, never indulging in sleep but on perpetual watch, intent on God, so as to understand the things that are and to comprehend the causes of each. But wisdom is also the interpreter of future things: “She knows the things of old and infers the things to come. She understands turns of speech and the solutions of riddles. She has foreknowledge of signs and wonders and of the outcome of seasons and times.” One who has obtained her, therefore, cannot but be good and perfect, because he possesses every virtue and is the very image of goodness. Even the sophists of this world drew from this text a definition of such a wise man: The wise man is (by definition) a good man and an accomplished communicator. . ...
After the tenth year he took Ishmael, his child by the maidservant, and considered that the promises had been fulfilled for him in the child. The patriarch was, you remember, the text tells us, eightysix years old when Ishmael was born. The loving God, however, exercised the virtue of the just man for a still further period of thirteen years. When God saw that he had been purified like gold in a furnace for a long period of time and had rendered the just man’s virtue more conspicuous and resplendent, Scripture says, “When Abram was ninetynine years old, God appeared to him again.” Why did God delay so long? Not simply that we should get to know the just man’s endurance and his great virtue, but for us to see as well the extraordinary degree of his power. You see, when nature lost its potency and was now useless for childbearing, his body being wasted and chilled with old age, God put into effect the promise to demonstrate his peculiar power. ...