After God finished his creation, he rested.
He then went to check on his creation and noticed Adam was bored, so he decided to do something about it.
The next morning, God called to Adam and said: "I have a surprise for you. Go through the forest, cross the river and walk around the mountain. On the other side of the mountain, there's a cave. Go inside and your surprise is waiting there."
Adam started walking and stopped. He turned around and said: "God, what is a forest?"
God said, "See all those trees and plants over there? That's a forest. Walk through it and when you get past it, you'll find the river."
Adam headed into the forest and some time later, came back and asked: "God, what is a river?"
God explained, "it is a body of running water. when you reach it, cross it to the other side and head to the mountain."
Adam takes off again and some hours later, comes back. "God, what is a mountain?"
God explains, "see that tall shape over there that forms a peak? That's the mountain."
Adam sets off again, only to return and ask: "I'm sorry God, but what is a cave?"
With yet another explanation, Adam heads out again.
Near the end of the day, Adam comes back once again and asks: "One more question, God: what is a headache?"