The great Lisbon earthquake of 1755 was the first great natural disaster to strike the heart of a large European city. For six minutes the earth shook, bringing down churches, palaces, and thousands of houses. After a 15-meter-high tsunami submerged the lower city, fires broke out and wrought more damage. The earthquake that laid waste to Portugal's capital city Lisbon on 1 November 1755 shook the West as severely as almost no other earthquake has before or since. This was not only because of the immense destruction it caused and the tens of thousands of lives it claimed, but because the event also affected European thinking over the long term by undermining the philosophical optimism of the Enlightenment, the belief in divine providence and the conviction of living in the best of all possible worlds.