Abel
Abel ("exhalation," or, "that which ascends") is a type of the spiritual man. His sacrifice, in which atoning blood was shed (Hebrews 9:22) was therefore at once his confession of sin and the expression of his faith in the interposition of a substitute (Hebrews 11:4).
flock
Type of Christ, the Lamb of God, the most constant type of the suffering Messiah -- "the Lamb of God that taketh away the sin of the world" (John 1:29).
A lamb fitly symbolizes the unresisting innocency and harmlessness of the Lord Jesus (Isaiah 53:7); (Luke 23:9); (Matthew 26:53); (Matthew 26:54). This type is brought into prominence by contrast with Cain's bloodless offering of the fruit of his own works, and proclaims, in the very infancy of the race, the primal truth that "without shedding of blood is no remission"; (Hebrews 9:22); (Hebrews 11:4).