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.

What remarkable experience attended the baptism of Jesus?
Why was further instruction concerning this vision necessary ?
What did some of the people do on the seventh day?
Through whom do we have sanctification?
When was the papal head of the first beast of Revelation 13 wounded?
On opening the fifth seal, what was seen under the altar?
What events mark the sounding of the seventh trumpet?

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