"FROM THE MIRRORS" Shemos 38:8)
This was not because there was no other source of copper, for we see that there was no want of materials of every kind. The women’s mirrors were given especial preference, because they entailed a sacrifice of considerable magnitude inasmuch as all women use mirrors.
There was another aspect which made the mirrors worthy of preference for the laver (the Kiyor). Just as the laver provided water for washing the hands and feet as a preparation for the service of Hashem, so also had the mirrors served as preparation for the service of Hashem. Unlike the nations of the world, Israel views the function of procreation with the most profound respect, as Chavah had said “I acquired a man for Hashem” (Bereishis 4:1).
Israel views the function of procreation with the most profound respect
The especial devotion of the women of Israel (see 1:15) to the ideal of producing a nation for the service of Hashem had made these mirrors an essential factor in encouraging procreation in Egypt when the sons of Israel were being crushed under the heel of oppression. Like the Kiyor, the mirrors had served as preparation for the most noble service of creating the nation of Hashem's servants. By means of these mirrors the women had beautified themselves in order to restore the spirits of their broken and downtrodden husbands; and thus the children of Israel continued to increase, despite the heavy oppression.
Marriage and children are in themselves the major forms of service to Hashem: “Was the world not created but for the purpose of Piryah and Rivyah״ (Gittin 4B).