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.

To whom does the \"seed\" in these promises refer?
Through what does grace reign unto eternal life?
And how should husbands regard their wives?
Can man of himself, unaided by Christ, keep the law?
Because evil is not punished immediately, what presumptuous course do many pursue?
Why does God wish us to trust in Jesus?
How long will there be poor in the world?

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