Margaret Edson said this quote

Classroom teaching withholds nothing. I say to my young students every year, “I know how to add two numbers, but I’m not going to tell you.” And they laugh and shout, “No!” That’s so absurd, so unthinkable. What do I have that I would not give to you?Bringing nothing, producing nothing, expecting nothing, withholding nothing — what does that remind you of? Is this a bizarre occurrence that will go into The Journal of Irreproducible Results? Or is it something that happens every day, all the time, all over the world,and is based not on gain and fame, but on love.