Simon Leys, The Hall of Uselessness
(Collingwood: Black Inc., 2012), p. 206:
The great modern Chinese writer Zhou Zuoren, whose essays are interspersed with a vast range of translations (Greek classics, classical and modern Japanese literature, English literature), developed this idea: a writer can translate various texts in order to give form to things he had in himself but which he could not find other means of expressing. This is why it is appropriate to include these translations in any collection of his own works. The same goes for the quotations and the notes on reading that certain writers accumulate, and that the English sometimes call a commonplace book (see for example that of E.M. Forster, published recently, or Montesquieu's Spicilège). String together all the pages that you have copied out over the course of your readings and, without there being a single line by you, the ensemble may turn out to be the most accurate portrait of your mind and your heart. Such mosaics of quotations resemble pictorial 'collages': all the elements are borrowed, but together they form original pictures.
Hat tip: Daniel Fertig.