As usual, Bonnie is paying attention. There is nothing to indicate any offering or sacrifice was required at all, much less any 'type' of one.The days in which God personally visited and spoke to man, must have been something. The fact that God spoke with Cain, and asked him some leading questions suggests to me that God was attempting to give insight to him AND his brother. He was trying to reveal himself to them.I wish Cain had asked, Why did you approve of Abel's sacrifice and reject mine? THIS is why my countenance has fallen.Even without him asking, God provided a learning opportunity: This is one of those times when I believe the NLT nails it: Gen 4:7You will be accepted if you do what is right. But if you refuse to do what is right, then watch out! Sin is crouching at the door, eager to control you. But you must subdue it and be its master.There are many who profess themselves to so much wiser than Cain, yet they still haven't learned this basic lesson from their creator.