Puzzle sunday (10)

This time I'm late with puzzle sunday. All because I'm working hard to try and sell my house. And the kids had their theater presentation yesterday.
OK. What is Phi? Well I'm not sure either. It is a greek letter and greek letters are often used in mathematical language. Mathematical language describes reality in a more formal way than does plain, prosaic or poetic language. Or doesn't it?

O, and if anyone of you is looking for a present for a smart boy, check this out! I'm sure I know one little boy that is going to love this!