When we think of friends, and call their faces out of the shadows, and their voices out of the echoes that faint along the corridors of memory, and do it without knowing why save that we love to do it, we content ourselves that that friendship is a Reality, and not a Fancy—that it is builded upon a rock, and not upon the sands that dissolve away with the ebbing tides and carry their monuments with them.

Mark Twain at Your Fingertips: A Book of Quotations (ed. Courier Corporation, 2012) - ISBN: 9780486123318