Smart client makes all happy

On This time project I take charge of two clients. One of them, there is so smart manager. He can understand the essential of the contents that I explain and make decisions quickly. Of course he ask the critical questions and criticize our ideas when I can't propose good ideas. But all time I get something that I should study. 
I think meeting good clients related to grow up. It's almost hard to work, but the experience make me strong. I'm so lucky. I believe this experience is treasure for my business life.