"The only certainty is that movement, change, and metamorphosis exists." —Andreas Treske, Video Theory

"We would do well to remind ourselves always that the only certainty is, as the physics joke goes, that Heisenberg may have been here." —Greg Goodale, The Rhetorical Invention of Man

"The only certainty is the possibility of doubt itself." —Ludwig Siep, Hegel's Phenomenology of Spirit

"The only certainty that is there is you. Why?—because even to doubt yourself, you have to be there." —Osho, Mindfulness in the Modern World

But what is the point? Despair is the only certainty here.

"Listen, you know as well as I do that the only certainty around here is that things are never going to get back to normal, don't you?" —David Moody, Autumn: The City (2011)

"The only certainty was the money."
—Christopher Farnsworth, The President's Vampire (2011)

"There is no absolute way to know if the dollar will go up, down or sideways—it may well do all of these things. The only certainty is that it will move." —Tim Weithers, Foreign Exchange (2011)

"The only certainty is that our current scientific models fail. Entirely."
—Brian Clegg, Gravity (2012)

"The only certainty is this: the more tricks you pull out of your bag, the greater the chance that one of them will backfire."  —Char Booth, Reflective Teaching (2011)

"The only certainty ... is that you'll never know if you could be one of them unless you try."
—Sherryl Woods, The Summer Garden (2012)

"The only certainty is that the utopian moment, if and when it finally arrives, will be the most satisfying of communions precisely because it has been sought out in a spirit of flexibility and mutual consideration."
—Robert Tobin, The Minority Voice (2012)