The desire to comment is a human impulse, seen also in art forms from music and visual art to film and literature. Syntaxes for commentary appear almost at once in the history of programming. Comments lie in the zone of the inexpressible, saying what cannot be said in a programming language, and the need for them can never entirely be designed away by new languages. The most audacious case for commentary remains Donald Knuth’s radical proposal for “literate programming”, which recasts the programmer as essayist. Emerging from Knuth’s thinking about ideas of perfectibility, publication, and the sacred, this manifesto was in part a rebuttal of structured programming. Though it failed to achieve dominance, its ideas remain stimulating, and show an eerie convergence with today’s norms – GitHub being in some respects its triumph after all. Practical experience with large-scale LP is mixed, but it still has much to teach us.