Miriam saved her baby brother's life. Her merit was always with him, his success always related to it. The water, made by her to save his life as an infant, stood by him always, in her merit. The fact that the people had water throughout their wanderings made his mission possible.
Chapter twenty of Bamidbar tells of the sin that Moshe committed, which made him unable to lead the Jewish People into the Promised Land. The chapter opens with the death of Miriam, his older sister. The next verse informs us that there was no water for the people, which caused them to gang up against Moshe and Aharon. Rashi (quoting the Gemara in Ta'anit 9a) tells us that there is a connection between these two pieces of information. For forty years the people received water in Miriam's merit. Now that she had passed away, they thirsted, because the well that had provided for them had disappeared.
It is easy to understand the connection between Miriam's merit and the supplying of water. Miriam stood guard when her baby brother, Moshe, floated down the Nile. Her meritorious deed was accomplished by using water, such that the water of the Nile would save the life of her brother. The people whom her brother took out of slavery therefore received water in her merit. When we use nature for the service of God, God sets nature at our service.
There is a closer connection between the issues. Ultimately, these people were saved because of Miriam. By using water in the service of God, she made her brother's mission, as a leader, possible. In the same way, his mission was always made possible through her merit. For her sake, water was supplied to the people in the desert, without which Moses would not have been able to lead them there for forty years.
This idea follows throughout the narrative, and opens a window into understanding fundamental issues later in the chapter. It was because of a lack of water that the people rose against Moshe and Aharon. God commanded them to speak to a rock, and when they hit it twice, and it still gave water, they were told that they had sinned - presumably, in diverting from the particular command. Not only was Moshe's mission hindered by the lack of water, by the lack of his sister's merit, but his whole leadership was challenged, and ultimately his mission was curtailed.
Miriam saved her baby brother's life. Her merit was always with him, his success always related to it. The water, made by her to save his life as an infant, stood by him always, in her merit. The fact that the people had water throughout their wanderings made his mission possible. As soon as this merit was lost, his mission was subject to the threat held off by that merit - the challenge of leadership over people without water. The complexity of the issue is remarkable. There is a direct correspondence, on several levels, between the nature of the valorous act performed, and its projected implications over time.
Courtesy of Yeshivat Har Etzion - www.etzion.org.il