Why did kandinsky paint squares with concentric circles?

When asked this he replied "I applied streaks and blobs of colours onto the canvas with a palette knife and I made them sing with all the intensity I could..."  Wassily Kandinsky "Color is the keyboard, the eyes are the harmonies, the soul is the piano with many strings. The artist is the hand that plays, touching one key or another, to cause vibrations in the soul." ~Wassily Kandinsky