Why is the origin of existence physical?

Leichtman—Well, why is there physical existence? 

Einstein—One of the major and all-encompassing reasons for physical existence is so that life can gain experience in manipulating and dealing in densermatter. It's akin to throwing a young child into a swimming pool so that the child can learn to swim. You watch it so it doesn't drown, but the purpose is for the child to learn to swim. In a sense, God has thrown Himself into physical matter and is attempting to learn to swim in it.

Einstein—Now, there are many imperfections physical matter. Many of the divine ideas have not been developed in physical matter fully to their final form. They are evolving toward the perfect idea, but they have not reached that stage yet. When the child is first thrown into the swimming pool, after all, it is quite enough that it thrashes about and stays afloat by doing the dog paddle. But eventually, the child would want to learn something better than the dog paddle—the perfect breaststroke—or whatever. In the same way, the life of God is thrashing about in physical matter. The concept of perfection for physical manifestation does exist in the mind of God, but what is actually being manifested through physical substance is less than perfect. It is moving toward perfection. 

ROBERT R. LEICHTMAN, M.D., From Heaven to Earth, EINSTEIN RETURNS, 1979, ARIEL PRESS THE PUBLISHING HOUSE OF LIGHT, COLUMBUS, OHIO, 18=19