HASHEM said to Moshe, “Say to Aaron, ‘Take your staff and stretch forth your hand over the waters of Egypt, over their rivers, over their canals, over their ponds, and over all their bodies of water, and they will become blood, and there will be blood throughout the entire land of Egypt, even in wood and in stone.’ ” (Shemos 7:19)
Say to Aaron: Since the Nile protected Moshe when he was cast into it, it therefore was not smitten by him, neither with blood nor with frogs, but was smitten by Aaron. — Rashi
And Aaron stretched forth his hand over the waters of Egypt, and the frogs came up and covered the land of Egypt. (Shemos 8:2)
HASHEM said to Moshe, “Say to Aaron, ‘Stretch forth your staff and strike the dust of the earth, and it shall become lice throughout the entire land of Egypt.’ “(Shemos 8:12)
Say to Aaron: It was inappropriate for the dust to be smitten through Moshe since it had protected him when he slew the Egyptian and had hidden him in the sand. [Therefore,] it was smitten through Aaron [instead]. – Rashi
Why was Aaron the one to deliver the first three Makos/Plagues on Egypt? Rashi spells it out very clearly. Moshe was saved by the waters of the Nile when he was placed there in a miniature Teva and discovered by the daughter of Pharaoh. The earth saved Moshe when he smote the Egyptian who was abusing a Jew and he buried him in the sand. The premise is, as the saying goes, “Don’t throw a rock into a well that you drank from.”
There is a gigantic question waiting to be asked here. The Nile is a river, a moving body of water. The water that saved Moshe is long gone and the plot of earth that saved him and helped cover up his deed was in a completely different place, and what would the water care and what would the earth mind if Moshe himself delivered the blow that launched the plague. Water and earth do not have feelings.
A few years ago, a young boy threw some garbage out of the second-floor window of the Yeshiva. It was not well received down below.
My assistant principal spoke to the boy. He landed an important message and it made a strong impression on the boy and on me. He asked the boy, “Why did the Teva, the Ark of Noach need to have three floors? One was for the people on the top and the animals in the middle and the bottom level was for garbage. Why did they need that bottom floor for garbage? It would have been a much more luxurious, sweet smelling, and spacious trip for all if the garbage was just thrown out of the window. Why didn’t they just throw the garbage out of the window? The world was completely flooded and being washed with the hot waters of the flood. It would not have soiled the earth in any noticeable way. Why not throw it out the window?!” That was his question!
The answer he gave was, “If they would have thrown the garbage out of the window, then it would have negatively impacted their character.” The new world would be built by sloppy and careless people. It’s not the environment but them at risk of being damaged.
The Sefer HaChinuch offers most often as the reason for a Mitzvah the principle, “HaAdam Nifal Achar Paulosov” – “A person is affected by whatever he does”. I saw a statement like this, “It is easier to act your way into a better way of feeling than to feel your way into a better way of acting.”
The Alter from Kelm explained that we are impacted by what we actually do and not by what we are theoretically doing. He recommends that a doctor should invest his spare time doing acts of kindliness because although he is helping people with his medicine, his experience all too often involves afflicting. He can become cruel and callous.
A student of the Chofetz Chaim was offered one of two seats in a Polish bank. In one seat he would be receiving deposits and at another he would be cashing checks. The Chofetz Chaim advised him to rather be handing out money to people on a daily basis because then he would be exercising the muscle of giving. Even though at the other seat he is theoretically helping people save money but by taking cash all day every day he would become a taker. Yes, Moshe would be helping with each hit but at what cost?!