Definition of Insanity?

I've heard two different commentators on the radio recently state that a definition of insanity is doing the same thing over and over and expecting different things to happen.

When I hand-saw through a piece of wood, I perform the same action over and over. For a while, it doesn't look like much is happening. Eventually, I cut through the piece.

I shorted a stock. It kept rising, I kept shorting. Was this insane? Eventually it went down like I thought it should.

The underlying problem here is that the things we act on in the real world often have state that isn't immediately apparent. We know it's there, we know we're acting on it, and we have to gauge the effects of our actions on that unknown state. Working with the unseen is common.