So the Lord said to Moses, “Say to Aaron, ‘stretch out your rod, and strike the dust of the land, so that it may become lice throughout all the land of Egypt.’” Exodus 8:16.
The frogs died and were then gathered together in heaps. Here the king and all Egypt had evidence which their vain philosophy could not dispose of, that this work was not accomplished by magic, but was a judgment from the God of heaven.
When the king was relieved of his immediate distress, he again stubbornly refused to let Israel go. Aaron, at the command of God, stretched out his hand and caused the dust of the earth to become lice throughout all the land of Egypt. Pharaoh called upon the magicians to do the same with their enchantments, but they could not.... The magicians themselves acknowledged that their imitative power was at an end, saying, “This is the finger of God.” But the king was still unmoved.
Still another trial was made, after another appeal to “let my people go.” Flies filled the houses and swarmed upon the ground, so that “the land was corrupted by reason of the swarm of flies.” These were not such flies as harmlessly annoy us at some seasons of the year, but they were large and venomous. Their sting was very painful to man and beast. It had been previously stated that the land of Goshen would be exempt from this visitation, which was accordingly found to be true.
Pharaoh now sent for the two brothers and told them that he would allow the Israelites to offer sacrifices in Egypt itself; but this offer was refused. Certain animals were regarded as objects of worship by the Egyptians, and such was the reverence in which these creatures were held that to slay one, even accidentally, was a crime punishable with death. Moses assured the king that it was impossible for them to sacrifice to God in the land of Egypt, for they might select for their offering some one of the animals which the Egyptians considered sacred.
Moses again proposed to go three days' journey into the wilderness. The king consented and begged the servants of God to entreat that the plague might be removed. They promised to do this but cautioned him against dealing deceitfully with them. The plague ceased at their prayer. But the king's heart had become hardened by his persistent rebellion, and he still refused to let the people go.—Signs of the Times, March 11, 1880.
From From the Heart - Page 216