I have loved the title of this post since I first picked up S.R. Ranganathan's "Five Laws of Library Science" back in library school in the early 90's. It is the motto of the Madras Library Association that first published Ranganathan's book back in 1931. A good image of it and the seal of the MLA has been scanned by a librarian at the Colorado College Tutt Library.
As a reference librarian, I am embarrassed to say that I am not sure what it means exactly or where the MLA found it (brownie points to the first reader who can provide the answer) but I am sure you get the point. My guess is it is another, far more poetic, way of saying knowledge is power (and I do know that is a derived from Francis Bacon's Meditationes Sacrae.)
Ranganathan was a remarkable man. A mathematician who became India's most famous and influential librarian. He promolgated his five laws in the context of a manual of library service. They are simple yet profound and I have found them to be important guideposts throughout my career.
Books are for use.
Every reader his or her book.
Every book its reader.
Save the time of the reader.
The Library is a growing organism.
The book (especially the 1931 edition) is now difficult to get hold of. I am afraid it is not in any local libraries and unavailable at any of the big online new and used book sellers. Copies are available in Florida State University and the State Library's collections. But I would wait for dLIST's digital version.