Genesis 4:21

And his brother’s name was Jubal: he was the father of all such as handle the harp and organ.

The verse stands in the fourth chapter of Genesis, in the account of what followed Cain as a tiller of the ground and Abel as a keeper of sheep. It belongs to the dark history after Cain's life was spared when he had merited death for murder, with opportunity granted for repentance. Cain only hardened his heart, encouraged rebellion against divine authority, and, led on by Satan, became the head and tempter of a line of bold, abandoned sinners. Jubal's handling of the harp and organ shows the distinction of Cain's descendants in mere earthly and material progress.

That progress belonged to a line that had gone out from the presence of the Lord, cast away the promise of the restored Eden, and sought possessions and enjoyment in the earth under the curse of sin, standing at the head of those who worship the god of this world, regardless of God and in opposition to His purposes for humanity. Their departure from plain commands spread by example and demoralizing influence until the world was filled with transgression, sin, corruption, and violence, and fifteen centuries after the sentence pronounced upon Cain the fruition of his influence appeared in crime and pollution flooding the earth, so that God destroyed the world. That history illustrates before the whole universe what permitting the sinner to live on forever in rebellion would bring, since forbearance only made the wicked more bold and defiant. It shows the sentence of death pronounced upon the fallen race for transgressing the law to be both just and merciful, because the longer people lived in sin the more abandoned they became, and the divine sentence cutting short a career of unbridled iniquity and freeing the world from the influence of those hardened in rebellion was a blessing rather than a curse.