I felt a Cleaving in my Mind — Jigsaw Puzzle

I felt a Cleaving in my Mind-1
As if my Brain had split-
I tried to match it-Seam by Seam-
But could not make it fit.

The thought behind, I strove to join 5
Unto the thought before-
But Sequence ravelled out of Sound
Like Balls-upon a Floor.
(F.867/J.937)
[1, 2] Cleaving, split:: a hint on puzzle with pieces of a cardboard.
[3, 4, 5] match, fit, join:: ways to solve the puzzle.
[6] thought before:: the original form of the puzzle before cut.
[7] out of Sound:: randomly.
[8] Balls, Floor:: pieces all alike spreading on the floor.