I am trying to track down the origin of the saying When all you have is a hammer, the whole world looks like a nail. After an hour of googling, I’ve got this:
“When the only tool you have is a hammer you tend to see every problem as a nail.” Abraham Maslow
“Give a child a hammer, and the world becomes a nail.” Jurgen Habermas
If all you have is a hammer, everything looks like a nail.
I have also seen it credited it to Mark Twain. Does anyone have an authoritative cite for the first appearance of this idea?