Hashem sent Moshe to bring the Makkos upon the Egyptians. However, for the first three Makkos, Aharon actually brought them. Rashi quotes the Midrash to explain: When Moshe was born, his mother placed him in the Nile to protect him from the Egyptians. Later, when Moshe killed the Egyptian overseer and buried him, the sand protected Moshe by hiding the body. Out of gratitude, Moshe could not hit the Nile or the sand. The first three plagues, which affected the Nile and the sand, had to be brought about by Aharon.
From here we learn an important lesson. Gratitude is owed even to inanimate objects-certainly to people as well.
But why is it important to show gratitude to inanimate objects? The sand would never know it had been hit. The water doesn't know it did Moshe a favor. Objects don't care if we are ungrateful, and the favors done through them are obviously unintentional.
To explain this, we must have a deeper understanding of gratitude. Rabbi Eliyahu Dessler offers us an insight.
Let's begin by explaining what gratitude is not. When a person receives a favor from someone and does not have gratitude, there may be several reasons. Perhaps he doesn't recognize that anything was given to him, or he feels entitled to it. Perhaps he feels that he is doing a favor to the giver by accepting, in which case why should he thank him? Only if the receiver understands that what was given to him was a sacrifice by another person, one that he isn't entitled to, will he express gratitude. And he is also motivated by the desire to continue to receive favors.
This gratitude is not real; it is rooted in selfishness. True gratitude is selfless. A person who only wants to be a giver is grateful for anything he receives. If someone does him a favor, he wants to give back irrespective of why the giver gave to him. As long as he received, he feels appreciation. This is why we need to show gratitude in a way that even goes beyond what we received.
But we still need to explain why gratitude must be shown to inanimate objects, which neither feel nor care if we are grateful.
Rabbi Dessler explains that our character traits are powered by sensitivity. If a person becomes desensitized in one aspect of a particular trait, his personality as a whole can be affected. If Moshe showed ingratitude to the Nile and to the sand, it would affect his gratitude to people, as well as to Hashem. The obligation of gratitude is not necessarily between man and his fellow; it is also between man and Hashem. It affects the person himself, not just the person to whom the gratitude is owed.
Taking this a step further, the first step of gratitude is realizing that a favor was done. This, in fact, is the literal meaning of the phrase "hakaras hatov"-recognizing the good.
Realizing that we have received a gift is a prerequisite to gratitude. It takes a keen and sensitive eye to recognize all of the good things that happen to us, especially small things that occur regularly and without the intention of the giver.
For an arrogant person who feels that he deserves everything, this is impossible. But Moshe was a very humble man. He didn't feel entitled to anything, so everything was seen as a favor. And he was grateful.
Often, we don't even realize that a favor is being done. But a person who is selfless and humble can easily recognize a gift, no matter how small it is.