Experiment is the sole source of truth. It alone can teach us something new: it alone can give us certainty. A quote from French mathematician and physicist Jules Henri Poincare (1854 - 1912) found in "The Foundations of Science", page 127, The Science Press, 1913. The quote also appears in "Statistically Speaking: A dictionary of quotations" compiled by Carl Gaither and Alma Cavazos-Gaither.