No rhyme or reason

In what sense the word "rhyme" has been used in the phrase "no rhyme or reason"?

A rhyme
keeps time.
When each line-end comes around,
Assonant, well-ordered sound,
We believe there must be matter, 'n'
We take comfort from the pattern.
Slave to the beat, we never roam,
Enraptured by the metronome.
Such a metrical profusion
Is a form of self-delusion.
Life is messy. It's chaotic.
Belief in order is neurotic.
(Reality has lousy timing)
So I guess I'll keep on rhyming,
Imposing order every season
Hoping rhyme will pass for reason.

Is that yours, Bob? Christ, you are an inventive s.o.b. Your answer is a tiny bit cryptic, but it seems right to me. SS