The Imagination Muscle

The imagination muscle sounds like a slightly gimmicky concept for the title of a book, but actually it comes from a... It's a quote from that book by John Claude Carrier. He found it sort of serendipitously by when he was browsing on Sharon Crossroad in the second-hand book shops while he was doing a job. But I'm not sure that the way the book pans out actually demonstrates that the imagination is a muscle. You might have been well asked you. What do I do? What do Ido? Do you know what I mean?