Midrash tells us that

When the waters of the Sea of Reads came rushing back over the Egyptian soldiers who were chasing the Israelites, angels in heaven made songs of joy and praise to celebrate, God hushed and rebuked them, saying "How can you sing songs of joy when my people are drowning?"  

We are reminded that we are all God's children, all part of something much larger thean ourselves.  As a token of sorrow at the loss of Egyptian life and loss to Egypt's ecosystem experienced in the Israelites' exodus to freedom, we dip our fingers to remove a bit of wine from our cups with a recitation for each of the ten plagues.


haggadah Section: -- Ten Plagues