A few quotes from Harry Mathews in those two interviews from the RCF.
HM: That’s one thing I learned from Roussel: that, in terms of storytelling, you can find masses of materials in solving absurd problems. Roussel had no qualms, and no plot. It’s all storytelling. It’s also highly poetic but the poetry is all there in absentia. It’s not there in what the text says it is doing. What the text says it is doing is telling utterly unlikely stories which at the same time have nothing gratuitous about them. You can tell by reading his books, even if he hadn’t written “How I Wrote Certain of My Books,” that he’s laboring under some kind of obligation, that he’s set himself conundrums to solve.
JA: Isn’t this what the Oulipo does? They invent rules which they observe strictly. What are the advantages of this?
HM: What I’ve always said–though I begin to doubt myself–is that it distracts the ego and the superego sufficiently to keep them busy on this arbitrary problem so that the unconscious is made available to the writer. Leiris said something like this about Roussel. He said that was why Roussel’s techniques were superior to that of the surrealists, because techniques like automatic writing were much too naive. The interesting thing about Breton is that his ideas about bringing the subconscious into art are marvelous but never affected the form of a single sentence he wrote. He wrote beautiful classical French and his poems are always elegant. But the definition of a constrictive form in the Oulipian sense is a form that will oblige you to write in a way that you wouldn’t possibly write in otherwise. That’s what the Oulipo is essentially about. This was particularly interesting in Perec’s case because he had such an extraordinary belief in writing. He really looked upon it as a kind of salvation.
“…Roussel showed me that you can generate prose works with the same kind of arbitrariness that you use in verse. One extraordinary thing about poetry is that, say, if you’re writing couplets, every five feet you have to have a word that sounds like another word, whether that makes any sense or not. You have arbitrary, illogical demands that you have to make on yourself. Roussel showed how this can be done in prose and so for me opened up the whole possibility of writing fiction, which I’d tried before without ever getting any place. I’d always thought that to write fiction you had to write more or less autobiographical stories, or stories of things that you’d observed in the world. It’s terribly hard to do that; at least it was terribly hard for me- to make it sing and glow. I think that’s why Roussel excited me so.”
“In Roussel, and in Oulipian work, you’re forced to do things you wouldn’t do otherwise, and this brings a great deal of freshness to them. One thing that I was inspired by in Roussel, most obviously in “The Conversation,” [sic, Conversions?] is that incredible voice, that very neutral, apparently indifferent tone in which the most insane things are said. This is one of those effects which is so potent.”