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.

In what event was this prophecy fulfilled?
By what is Grecia, the kingdom succeeding Medo-Persia, represented in the image?
What did this power do to the truth?
And how may we know that we love the brethren?
How is the closing period of tribulation of the church during this time referred to?
What were the colour and character of the fourth symbol?
In what is the wrath of God filled up?

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