Elder Arin:
Welcome, young apprentice! Do you have the fifty floating stones that I asked you to collect? Ah, right! You certainly have fifty of them! Thank you for your trouble. I will pay you as promised. This should be enough.
Now I can have some time to concentrate on my study. I don't know what will happen when the material runs short again, but once the ultimate airship is ready I will call you and give you a ride. So come visit me from time to time, and help me collect research materials.