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.

By what means are sins washed away?
What was required in order to effect this reconciliation?
For what purpose is the mystery of the gospel made manifest?
What is promised those who honor their father and their mother?
Why was double manna given on the sixth day?
12. Are men's hearts now \"failing them for fear, and for looking after those things which are coming on the earth\"?
Whom will they be like?

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