The late statistician George E.P. Box, who famously wrote that “all models are wrong, but some are useful,” also wrote that “science is a means whereby learning is achieved, not by mere theoretical speculation on the one hand, nor by the undirected accumulation of practical facts on the other, but rather by a motivated iteration between theory and practice.”
http://www.the-scientist.com/?articles.view/articleNo/37154/title/Why-Women-Lose-Fertility/