@davidnasser @mingk @leebryant @kaldajani and many others have tweeted the following aphorism.
'Knowledge is knowing a tomato is a fruit. Wisdom is knowing not to put it in a fruit salad."
Please permit me to quibble with this aphorism. Classifying tomatoes as fruit is merely information. This classification is supported by data, such as the observation that the tomato contains its own seeds. Knowing not to put it into a fruit salad is a culinary "best practice", based on a series of social conventions about the proper constitution of fruit salad and its place within a meal. So this is knowledge, or what is sometimes called "received wisdom". However, innovation often involves disobeying social conventions and surprising those who rely excessively upon received wisdom. For example, how did chefs discover that it was okay to put flower petals into salads ("next practice")? So courage is knowing that you are not "supposed" to put tomatoes into fruit salad, but doing it anyway. And real wisdom is not inflicting such gross culinary experiments on the wrong people at the wrong time in the wrong way.
Wikipedia attributes this aphorism to the Irish rugby captain Brian O'Driscoll. Various interpretations can be found in the comments to Brendan Cole's blog What did BOD mean? (Feb 2009)
On the Unbelievable Truth (Series 10 Episode 5), the @RealDMitchell rants about whether a tomato is a fruit or a vegetable. He claims that the US Government taxes tomatoes as vegetables, and regards this as more authoritative than mere science.
See also my post Co-Production of Data and Knowledge (Nov 2012)
Updated 29 January 2013