G‑d’s battering of the Egyptians began with the waters of the Nile turning into blood. Next, G‑d smote the land with a plague of frogs, which swarmed from the waters of the Nile into the Egyptians’ homes, bedrooms and kitchens.
The Torah’s name for Egypt, Mitzrayim, shares a common root with the Hebrew word meitzar, constraint. Accordingly, the ten plagues that brought down mighty Egypt represent the steps we must take to break out of our personal “Egypts”—the internal limitations that hinder and constrain our service of G‑d.
The first two plagues both involved water. Water, which is cold by nature, symbolizes an attitude of coolness—detachment and indifference. The first plague, in which the waters of the Nile were transformed to warm and lifegiving blood, symbolizes that we must imbue our service of G‑d with warmth and excitement. In contrast, the second plague, in which creatures of the water, frogs, swarmed, everything related to Pharaoh and Egypt—and particularly, their ovens—symbolizes that breaking through our internal “Egypts” requires developing a coolness towards material pleasures.
Now, under normal circumstances, ridding ourselves of competing loyalties—symbolized by the plague of frogs—would be the first step to take before attempting to live a life devoted to G‑d and G‑dliness. We see, however, that the plague of frogs was not the first plague but the second; the plague of blood preceded it. The order of these two plagues teaches that even before we have succeeded at cooling down our material pleasures, we must already infuse our Torah and mitzvos with fervor, for the light and warmth of our passion‑filled mitzvos will assist in dispelling any dark and undesirable passions that remain.
—Likkutei Sichos, vol. 1, pp. 123–125