Correlation is not causation. Really?

"Correlation is not causation." Is that a true statement?

Edward R. Tufte says, "In fact, probably the shortest true statement that can be made about causality and correlation is "Empirically observed covariance is a necessary but not sufficient condition for causality."

Edward R. Tufte, "The Cognitive Style of PowerPoint: Pitching Out Corrupts Within," second edition, January 2006.