From Richard Thaler and Cass Sunstein’s Nudge:

To analyze this question, let’s start with a simple example inspired by a wonderful poem by Shel Silverstein entitled “Smart.” The poem is fun as well as brilliant, so if you have a computer nearby, we suggest that you type “Smart” and “Shel Silverstein” into Google and read the poem now.*

* Silverstein had personally given Thaler permission to use the poem in an academic paper published in 1985–he said he was tickled to see his work appear in the American Economic Review–but the poem is now controlled by his estate, which, after several desperate nudges (otherwise known as desperate pleas), has denied us permission to reprint the poem here. Since we would have been happy to pay royalties, unlike the Web sites you will find via Google, we can only guess that the managers of the estate (to paraphrase the poem) don’t know that some is more than one.