This audio clip is from Loraine Boettner’s The Reformed Doctrine of Predestination, from the long section covering common objections to this Bible teaching. The particular objection considered here is the errant charge that predestination makes God the author of sin. The clip is from chapter 17: “That It Makes God The Author of Sin,” and is found in the section of that chapter: “Calvinism Offers A More Satisfactory Solution of the Problem of Evil Than Does Any Other System.”
These are deep things, but they are knowable (at least in part), because God has revealed them to us in his word. We would do well to practice more complete adoration rather than attempting a complete explanation.