CAIN AND ABEL

The first two children of Adam and Eve. Cain was involved in agriculture being a tiller of the soil, while Abel the second son of Adam and Eve, was a shepherd. They both made offerings to God. Abel, sacrificed the firstborn of the lambs and was acceptable to God, whereas Cain's offering of corn (or other fruit of the earth) was rejected because it was a second rate produce.
Overcome by jealousy over the non-acceptance of his offering and over a twin sister whom Abel had married, Cain enticed Abel into the open country and murdered him, according to tradition with the jawbone of an ass. (Genesis 4:1-8). When asked by God where his brother was he said: "Am I my brother's keeper?" (Genesis 4:9).
Cain was not only responsible for the death of Abel but also for the death of Abel's descendants who would never be born. That is why the Bible states that the "bloods" of Abel cried out to God from earth.
For this sin of fratricide Cain lost his portion in the World to Come. He was cursed by God to wander the face of the earth, finding no rest, but he carried God's mark on him so that no one would kill him, and he grew horns to scare off any animals that might attack him (Wandering Jew).
Cain himself was really the child of Eve and the serpent, and his descendants show some of the wicked characteristics of their ancestor. It was eventually his own descendant, Lamech, who killed him with an arrow, having been misinformed that the horned Cain was himself a wild animal.
God instituted a World Order which Man must respect. Everything in God's creation has its own place and must not be interfered with by Man's wrong interpretation of it.
These two sons of Adam and Eve were totally different types, Cain represented the evil power in the form of cloth crafted from wool and linen threads which were prohibited to be worn because of the laws of mixed species (Leviticus 19:19; Deuteronomy 22:11), and Abel represented the power of holiness through the representation of clothes made only of pure wool.
The connection found between cloth made of wool and linen (shaatnez) and the ones of pure wool symbolizes the story of Cain and Abel. Cain was a tiller of the ground whose offerings to God were of flax and a number of mixed products, while Abel was a shepherd, who offered up only the best of its wool. The combination of the brothers' powers in their mother's womb led to the tragedy of fratricide. Similarly, anyone wearing the linen-wool combination in a symbolic way is likely to come to harm and others wearing pure wool is likely to come to do goodness to others.
Attempts were made to explain the origins of the prohibition in terms of the clothing spiritually used in idolatrous cults, which spiritual Jews were meant to avoid.
Adam and Eve are shown lamenting Abel's death. They were comforted when their son Seth was born.
Abel is an Old Testament of Christ, Shepherd of Mankind. His violent death foreshadows the Crucifixion. Jesus placed Abel first in the line of Old Testament martyrs. (Matthew 23:35). He was one of the Just released from Limbo by Christ at the time of the Descent into Hell.