Little Black Classics Carry Penguin to New Heights

Released to mark Penguin Books' 80th birthday, the pocket-sized, 80p-a-pop Little Black Classics have been a hit, selling 70,545 copies in the first week of publication.

The commercial success of the commute-length gobbets - 80 titles ranging from the Communist Manifesto to Sappho's poems to Mozart's letters to his father - is striking since they are all in the public domain. To quote a commenter on the Guardian website: "How many of these are not available in full on Project Gutenberg?"

How to explain the appeal? Partly it's the curation; but it also proves people like their reading matter cheap... and portable.