Job 4:8

Even as I have seen, they that plow iniquity, and sow wickedness, reap the same.

Those who plow iniquity and sow wickedness bring punishment upon themselves by a fixed result, reaping the same evil they planted. Disregard of the light and evidence God has given creates moral darkness, and the shadow that follows is darker because light had been sent. Pharaoh illustrates this, for he yielded while the plagues were upon the land but rejected the evidence when they were removed, and then darkness came upon him.

God did not confirm Pharaoh in impenitence. When a person withdraws from light and yields to seduction, he draws unbelief around himself until he can no longer distinguish light from darkness. For such a person greater evidence is misunderstood and only increases indifference, until the deceived soul mistakes darkness for light and truth for error. The end of that course is fear arriving as utter ruin and destruction striking like a violent windstorm, when those who hated knowledge and despised reproof are left to be filled with the results of their own choices.