A demonstration of the damping effect of an oil monolayer on water waves is described. The history of this remarkable demonstration--with a 2000 (or more) year span--and a brief explanation in terms of the properties of water and the monolayer are presented. If a layer of olive oil, one molecule thick (about one-ten millionth of a centimeter), is applied to the surface of rough water, the waves are dramatically calmed. The amazing ability of a film one molecule thick to dissipate the relatively large energy of water waves can be readily demonstrated, but an explanation of the effect has been elusive until recently. (Contains 1 figure and 6 notes.)