«وكان البرق مصحف قار»
And the lightning was like a reciter’s manuscript.
The source develops the image through the book’s opening and closing. Its pages move in different directions as the codex opens and shuts, forming a composite moving configuration.
The image is not explained simply by the general definition of a manuscript. Rather, the specific sequence and opposition of the page movements helps express the appearance and disappearance of a flash of lightning. It is the coordinated motions, not just the noun “book,” that make the simile intelligible.