Chapter 7 starts with the Lord giving Moses and Aaron a brief sketch of what to expect: God will harden Pharaoh's heart and none of the miraculous signs from God will sway the king. But then the Lord will bring out the Israelites and, in so doing, the Egyptians will know that the God of the Israelites is a whole lot more God than their idols! And then there is the comment that Moses was 80 and Aaron 83 when this took place. Miriam, who would also be with them, would have been even older, for it was she who had watched her little brother's basket on the Nile that fateful day when the Pharaoh's daughter had seen it! Next, we've got a little problem with the English language again -- in all translations. In Exodus 4, Moses was told to throw down his staff, and it became a snake. Here in Exodus 7, Aaron is to throw down his staff and it becomes a snake. Two different words for snake, folks! In Exodus 4, the word was nahas, meaning snake as you and I know them, crawling along the ground, and also used for a poisonous snake, which we are presuming it was in Exodus 4 because Moses ran from it. In Exodus 7, Aaron's rod becomes a tanniyn, or monster! It is the same word used in Genesis 1 denoting the great creatures of the sea! It is also translated several times, however, as snake. The magicians' rods also become 'tanniyn'. So what they actually became is unknown to us. HOW they became this thing was either through sleight of hand or demonic arts (the magicians, not Aaron!). So Aaron's staff and Moses' staff were changed into two different things by the Lord. This is emphasized a little later in chapter seven, verse 15, when the Lord tells MOSES to meet Pharaoh in the morning going down to the Nile and to take his (Moses') staff with him and throw it to the ground and it will become a nahas again. However it is the raising of AARON's staff that turns the waters to blood. Were they really blood? Many will say yes. I would suggest that if something appears rather thick, red, and salty, you might just assume it was blood without a lab test to verify it... In other words, the waters on the surface of the ground gave the appearance and consistency of blood for the first plague. There are two interesting points here: the magicians were able to do the same, and the people had to dig for fresh water. To me this indicates that the event was timed by Aaron's rod, but not caused by it, but rather from something outside, as the magicians seemed to be able to do the same thing. This is possibly supported by the fact that only surface water was affected; the underground water remained pure. Even water in buckets and jars became this blood-type of thing. It may have been a flat-out miracle with no external 'cause' whatsoever. I will never deny that. However, given that as a distinct possibility, I am also curious about other possibilities. There have been a number of theories proposed through time: that we passed through the tail of a comet at that point and the material in the tail did this to the waters; that the waters were contaminated by a massive volcanic explosion not far away (a second explosion would explain the 'trick' accomplished by the court magicians); and a number of other things. Whatever it was killed the fish. And, fish being fish, they started to rot almost instantly, and it is because of the rot smell that the Bible tells us the people could not drink the water of the Nile. We often assume it is because it looked like blood, but that is not the reason the Bible gives! And Pharaoh? He refused to pay attention to this problem and the Bible says his heart became hard, just as the Lord had said. What did he do? Retreated into his palace, into his own 'comfort zone' while his people were frantically digging along the banks of the Nile looking for uncontaminated water to drink!