"A meaningful photograph - a successful photograph - does one of several things. It allows, or forces, the viewer to see something that he has looked at many times without really seeing ; it shows him something he has never previously encountered ; or, it raises questions - perhaps ambiguous or unanswerable - that create mysteries, doubts, or uncertainties. In other words, it expands our vision and our thoughts. It extends our horizons. It evoques awe, wonder, amusement, compassion, horror, or any of a thousand responses. It sheds new light on our world, raises questions about our world, or creates its own world."
Bruce BARNBAUM, The Art of Photography, An Approach to Personal Expression, Santa Barbara, Rockynook, 2010, p. 2.