“Books are the windows through which the soul looks out. A house without books is like a room without windows.”

Attributed to Cicero in J. M. Braude's Speaker's Desk Book of Quips, Quotes, & Anecdotes (Jaico Pub. House, 1966), p. 52.
Dennis McHenry in a 2011 post at theCAMPVS.com http://thecampvs.com/2011/08/03/cicero-on-books-and-the-soul/ identified a source for the exact form of words in the essay "On the Pleasure of Reading" http://books.google.com/books?id=0YfQAAAAMAAJ&dq=cicero%20%22room%20without%20books%22%20%2B%22contemporary%20review%22&pg=PA240#v=onepage&q&f=false by Sir John Lubbock, published in The Contemporary Review, vol. 49 (1886) https://archive.org/details/contemporaryrev55unkngoog, pp. 240–51 https://archive.org/stream/contemporaryrev55unkngoog#page/n250/mode/2up, in which Lubbock wrote that "Cicero described a room without books as a body without a soul" (p. 241). The same sentence may also be found on p. 61 https://archive.org/stream/thepleasuresofli01lubbuoft#page/60/mode/2up of Lubbock's collection The Pleasures of Life. Part I. 18th edition (London and New York : Macmillan and Co. 1890) https://archive.org/details/thepleasuresofli01lubbuoft, in a lecture titled "A Song of Books". McHenry suggested that Lubbock may have had in mind the words "postea vero quam Tyrannio mihi libros disposuit mens addita videtur meis aedibus" at Cicero, Ad Atticum 4.8, which are translated by E. O. Winstedt on p. 293 https://archive.org/stream/letterstoatticus01ciceuoft#page/292/mode/2up of Cicero: Letters to Atticus I (London : William Heinemann, and New York : G. P. Putnam's Sons 1912) https://archive.org/details/letterstoatticus01ciceuoft "Since Tyrannio has arranged my books, the house seems to have acquired a soul", and by Evelyn Shuckburgh on p. 234 https://archive.org/stream/cu31924012541433#page/n283/mode/2up of The Letters of Cicero. Vol. I. B. C. 68–52 (London : George Bell and Sons 1908) https://archive.org/details/cu31924012541433 "Moreover, since Tyrannio has arranged my books for me, my house seems to have had a soul added to it" (although the Latin word " mens http://athirdway.com/glossa/?s=mens", rendered "soul" by both Winstedt and Shuckburgh, is more usually translated by the English "mind"). D. R. Shackleton Bailey in Cicero's Letters to Atticus (Harmondsworth : Penguin Books 1978), p. 162, translated "And now that Tyrannio has put my books straight, my house seems to have woken to life".
Disputed
Variant: Ut conclave sine libris ita corpus sine anima" A room without books is like a body without a soul