Waka-Dharani Theory
Interesting follow-up reading on the power of poetry: "Reading the Miraculous Powers of Japanese Poetry: Spells, Truth Acts, and a Medieval Buddhist Poetics of the Supernatural," [PDF] by R. Keller Kimbrough (lots more to read at the link, too).
Miraculous poems — specifically those reported to have been efficacious in moving demons and deities — can generally be divided into two categories: those that function spontaneously, independent of the poet's wishes, and those that are reported to have been crafted by the poet with an intent to produce a supernatural result. Of poems in the former category, most are represented as having been effective because of the emotional response that they inspire: a deity, inadvertently moved by the grief or longing of the poet, typically exercises its powers on the poet’s behalf. Poems in the latter category tend to employ a variety of approaches: while many appeal to sentiment, others are composed to flatter, threaten, blackmail, and possibly even confuse. [...]
無名酒:
RYOKAN used CONFUSING POEM.
It's super effective!