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 kind of teaching have men substituted for the words which are spirit and life?
Of what besides a knowledge of God as Creator, is the Sabbath a sign?
What was the color of the symbol under the third seal?
What becomes of man's thoughts at death?
In what work are angels engaged?
What did He say to the woman of Samaria as to the source of salvation?
What does Daniel say of this kingdom?

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