The Lord turn his face towards you and grant you peace. The medical men present here today will, I hope, consider it no slight on them when I say that I hope that they are able to cope with plagues in their way as efficiently as today you coped with the Ten Plagues in your way. Your reading of the entire portion involved much work cheerfully done, and you deserve much credit. This would have been a proud day indeed for your maternal grandfather, had he been spared to see it. I am going to speak to you today about just one of the plagues which you enumerated.
Holy scripture describes first the plague of blood.
All the waters of the land of Egypt became blood, that which was in their streams and rivers, their ponds and pools, and even in their vessels. It is a pity that they did not know about blood transfusions in those days, because their physicians would just have had to hook up their patients to the kitchen faucet. Now this incident allowed the rabbis to give free reign to their imagination. In the Midrash, they declare that if an Egyptian and an Israelite were in one house where there was a barrel full of water, and the Egyptian went to fill a pitcher from it, he would discover that it contained blood, but the Israelite would drink water from the same barrel, since he was exempt from the plague. Only if he purchased it from the Israelite for money, was he able to drink the water.