Here is an anecdote told by Hazrat Inayat Khan of a brief exchange he once had with someone.  He frequently used the metaphor of digging in the earth in search of water to illustrate the spiritual work of opening the heart.

Someone came to me and said, “I was very sympathetic once, but somehow I have become hardened.  What is the reason for it?”

I said, “You tried to get water from the bottom of the earth.  But instead of digging deep down, you dug in the mud, and you were disappointed. If you have patience to dig till you reach water then you will not be disappointed.”