The Divine Institution of Marriage between Man and Wife - Genesis 2:24
24Therefore shall a man leave his father and his mother, and shall cleave unto his wife: and they shall be one flesh.
God caused deep sleep to fall on Adam. He then brought the woman to the man. She was his second self, a help-mate for him. How good was God to him! How good was God to bring him a companion that was human like him, but created different for a reason.
She completed him, being his companion that was not created from his head to top him, or his feet to be under him, but from his rib to be beside him, yet under his arm to be protected by him.