My Brother's Keeper
“What have you done? Listen! Your brother’s blood cries out to me from the ground. Now you are under a curse and driven from the ground, which opened its mouth to receive your brother’s blood from your hand. When you work the ground, it will no longer yield its crops for you. You will be a restless wanderer on the earth.”
Most people have a general knowledge of who Cain was and what he did. Who he actually was is the first born of Adam and Eve and the first naturally born man on Earth. He never knew what it was like to live in the garden. Since he never got the chance to see God face to face, there was a level of faith required by him that his parents didn't need, which makes it easier to understand his heart and how he could ever murder his own brother. Not to say that murdering someone can be excused by someones upbringing, but simply how a life apart from God leads people to do unbelievably cruel and evil things.
Cain was a farmer. In order to be successful at that job he had to have woken up early every day, worked in the hot sun, and broke his back digging and carrying things all day. He ended his days aching and sore just to fall asleep to do it all over again. It’s a job with a lot of work that takes a long time before reaping any kind of reward. His brother Abel was a shepherd. While it’s not exactly easy caring for mindless sheep all day, it’s not as difficult as breaking your back all day farming. I imagine there’s a lot more down time caring for sheep and probably more time to spend meditating and communing with God. I also imagine, after working all day long, Cain probably felt bitter knowing that his life was not supposed to be so hard. He probably blamed his parents and maybe even shook his fists at God with the thought that it was not his fault his parents didn’t obey.