Lake without water.
An image of Exhausting.
In correspondence with this,
The superior person spares no effort
in fulfilling his inspiration.
I wonder why hexagram 47 is an image of exhaustion? The nature of water is to flow downwards while a lake is stay still. The lakes that I have in my mind are rather serene and calm. They don't move per se. So, if water (the bottom gua) from the lake (the above gua) is getting away from the lake, we have an image of a lake that's being drained. That's why Confucius states "An image of Exhausting."
The primary attribute of lake is joyousness while that of water is danger and hardship. When you mix these attributes together, there's not much joyousness.
Let's look at the Chinese Character, 困. It's wood inside an enclosure, boundary. It's been fenced off, trapped. It can't move around. It is restricted and limited. Unless it is released, in the end, it will be become exhausted and die.