Wallace Stevens, motivational speaker
A web site called PinoyBusiness.ORG, for "Global Filipino Business and Investing Community," has a daily feature that provides motivational sayings, a link to "free motivational quotes," another link to "Harness Your Own Power," and finally a link to "Depression Quotes" (presumably meaning an emotional rather than financial crisis). Today's motivational saying is from Wallace Stevens: "The summer night is like a perfection of thought." I suppose in January this does motivate one...to daydream of a better moment.
The line is from "The House is Quiet and the World is Calm," a late poem that actually celebrates, if anything, the final rest of the old reader-poet. No blazing artifice there.
A little further googling and I realize that the line has been passed around from web hand to web hand, obviously further and further from its context, until it is simply axiomatic that it's a "motivational saying." It is, for instance, "Quotation #31277 from Laura Moncur's Motivational Quotations." This is one of those rare moments when I wish Stevens was still around to respond to such "use" of his poetry. He would surely fire off a quip that would be memorable in itself. The world is not calm.