A great TED talk below (17 minutes or so) from Steven Johnson on how great ideas come about.
Johnson argues that there is no eureka! moment and that “chance favors the connected mind.” Sometimes ideas linger on in people’s heads for years before they are fully formed.
Another point he makes is that ideas usually come in group situations. Researchers in a lab make most of their breakthroughs at weekly meetings when they hash over their problems with co-workers.
As far as those situations go, Johnson said the Enlightenment came about from two main sources. Back then, water was unsafe to drink and the main beverage was alcohol based i.e beer with breakfast, wine with lunch and so on. The introduction of tea and coffee to the west saw a change in outlook. Equally important was the architecture of the new coffee houses. Chance meetings occurred, there was an air of discovery and intellectual stimulation. It was where “ideas could have sex.”
But don’t take my word for it. Watch the video.