The Engineer and the Mathematician (a joke)

I could not resist including this joke, widely told among mathematicians. Besides, life is incomplete without a sufficient dose of humor...

An engineer is asked the following question:
"You are in a modern kitchen, with an empty pot, and need to produce 2 quarts of boiling water. How would you do this?"
Replied the engineer, "Fill the pot with at least 2 quarts of water from the tap, put the pot on the stove, turn on the stove, and wait for the water to heat up to the boiling point."
A mathematician is asked the same question, to which he replies, precisely in the words of the engineer, "Fill the pot with at least 2 quarts of water from the tap, put the pot on the stove, turn on the stove, and wait for the water to heat up to the boiling point."

The questioner now returns to the engineer, and asks the follow-up question:
"Now imagine you are in the same kitchen, but the pot is already filled with at least 2 quarts of water. How would you produce 2 quarts of boiling water."
Replied the engineer, "The task is simpler! Put the pot of water on the stove, turn on the stove, and wait for the water to heat up to the boiling point."
The mathematician is asked the same follow-up question, to which he replies:
"Take the pot of water, pour it into the sink- down the drain- and put the empty pot down on the counter. Now it reduces to the previous case!"