And he shall dwell in that city, until he stands before the congregation for judgment, and until the death of the high priest that shall be in those days: then shall the slayer return, and come unto his own city, and unto his own house, unto the city from where he fled.
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Ambrose of Milan
AD 397
There remains … what Scripture says concerning the death of the chief priest, “that the homicide shall be in the city of refuge even to that time, until the high priest dies.” In this passage the literal interpretation causes difficulty. First, the period of flight is limited by chance rather than by any consideration of fairness; further, in like cases the result is unlike. For it could happen that the high priest might die on the day after the homicide took refuge. However, what is the meaning beneath the uncertainty? And so, because the letter causes difficulty, let us search for spiritual meanings. Who is that high priest but the Son of God, the Word of God? We enjoy his advocacy in our behalf before the Father, for he is free from every offense, both willed and unintentional, and in him subsist all things which are on earth and which are in heaven. For all things have been bound by the bond of the Word and are held together by his power and subsist in him, because in him they have...
Fact. Septuagint, "before the synagogue for judgment. "(Haydock)
Whether this took place in the same city, or where the murder was committed, (see Numbers xxxv. 12, 25.) the reasons are given why the manslayer was released at the death of the high priest. (Calmet)
By the death of Christ, the greatest criminals are redeemed. (Menochius)
For the very words of Scripture indicate that even ignorance is a sin. [Thus], also, Job offers burnt offerings for his sons, [in the event] they may have sinned unwittingly in thought. And, if a man is killed by the iron of an axe that flies off the handle when a man is hewing wood, the wood hewer is ordered to flee to a city of refuge and remain in that place until the death of the high priest, that is to say, until he is redeemed by the blood of the Savior, either in the house of baptism or by repentance, which supplies the efficacy of the grace of baptism through the ineffable mercy of the Savior who does not wish anybody to perish. Nor does he find his delight in the death of sinners, but rather that they be converted from their way and live. - "Defense Against the Pelagians 1.33"