How early was this sacrificial system known?

Answer

"By faith Abel offered unto God a more excellent sacrifice than Cain, by which he obtained witness that he
was righteous, God testifying of his gifts." Heb. 11: 4. See Gen. 4: 3-5; 8: 20.

How was Christ's first advent to be heralded?
What is the very life of the Spirit?
Following one of His parables, what did Christ say?
What high ideal should he placed before the young?
What is the essential principle of the law of God?
Is Christ coming again?
What shows that the actions of men are recorded?

Questions & Answers are from the book Bible Readings for the Home Circle