Exodus 8:15 says, But when Pharaoh saw that there was respite, he hardened his heart, and hearkened not unto them; as the LORD had said.  Pharaoh once again reneged on his promise.  There are many people today who will promise God anything when they are in trouble, but as soon as the trouble passes, they will forget everything they promised Him.  Verse sixteen says, And the LORD said unto Moses, Say unto Aaron, Stretch out thy rod, and smite the dust of the land, that it may become lice throughout all the land of Egypt.  God next told Moses to have Aaron hit the dust of the land and it would become lice. This would once again be something that would make all the people miserable and would not just affect Pharaoh alone.  Sins of the leaders of countries often affect the entire nation.  Verse seventeen declares, And they did so; for Aaron stretched out his hand with his rod, and smote the dust of the earth, and it became lice in man, and in beast; all the dust of the land became lice throughout all the land of Egypt.  Once more when Aaron did as God directed, God delivered on his promise, just as He will for us today.  Verse eighteen adds, And the magicians did so with their enchantments to bring forth lice, but they could not: so there were lice upon man, and upon beast.  This time, the magicians of Egypt were unable to duplicate the event.  There is a limit on how much the world can duplicate the acts of God.  Verse nineteen states, Then the magicians said unto Pharaoh, This is the finger of God: and Pharaoh’s heart was hardened, and he hearkened not unto them; as the LORD had said.  The magicians finally admitted that what had happened was an act of God, but Pharaoh still hardened his heart against believing.  Verse twenty declares, And the LORD said unto Moses, Rise up early in the morning, and stand before Pharaoh; lo, he cometh forth to the water; and say unto him, Thus saith the LORD, Let my people go, that they may serve me.  God once again sent Moses to Pharaoh to tell him that God said for Pharaoh to let His people go.  God will always give people plenty of opportunities to obey Him and let the sin in their lives go.  Verse twenty-one adds, Else, if thou wilt not let my people go, behold, I will send swarms of flies upon thee, and upon thy servants, and upon thy people, and into thy houses: and the houses of the Egyptians shall be full of swarms of flies, and also the ground whereon they are.  God once again had Moses tell Pharaoh what would happen if he didn't obey, and that was swarms of flies.  Verse twenty-two adds,  And I will sever in that day the land of Goshen, in which my people dwell, that no swarms of flies shall be there; to the end thou mayest know that I am the LORD in the midst of the earth.  God said that He would separate the land of Goshen, where His people lived, and they would not be infested with flies.  God said that this would show Pharaoh that God was indeed the God of the universe.  Though it may not be as drastic, God stills makes Himself known to the world today by our faith in Him.  As with Pharaoh, no matter what signs God gives us today, we can either believe that He is God by faith or reject Him from the hardness of our heart.  Verse twenty-three continues, And I will put a division between my people and thy people: tomorrow shall this sign be.  Then verse twent-four concludes, And the LORD did so; and there came a grievous swarm of flies into the house of Pharaoh, and into his servants’ houses, and into all the land of Egypt: the land was corrupted by reason of the swarm of flies.  God again said He was going to separate His people from the coming plague, and then He did what He said.  Aaron did not have to do anything this time, so there could be no doubt that it was God causing the swarms of flies to happen,  God still makes Himself known to people today, but many refuse to believe and harden their heart against Him.