Mrs Merkel was speaking at the inauguration of an exhibition in Berlin to commemorate eight decades since Hitler became chancellor on January 30, 1933 - an anniversary which has aroused much interest in Germany.
"Human rights don't assert themselves. Freedom doesn't preserve itself all alone and democracy doesn't succeed by itself," Mrs Merkel said.
"That must be a constant warning for us, Germans," she added referring to Hitler's arrival at the chancellery.
Der Spiegel, meanwhile, explains how it wasn’t so clear to diplomats in Berlin in 1933 what an unmitigated disaster Hitler’s rise would be. In fact, it wasn’t even clear the Nazi-led government would last long:
Along with other observers, diplomats in Berlin in 1933 did not immediately recognize that the appointment of the new government marked a historical turning point. At that early stage, no one predicted that the Nazi regime would last for 12 years and end with a disaster on the scale of World War II. Initially, Hitler's cabinet was viewed as just another in a series of more or less short-lived German governments…
In [US Ambassador Frederic] Sackett's opinion, the real power lay in the hands of Vice-Chancellor Franz von Papen and Minister for Economics Alfred Hugenberg. It was a view that echoed his American colleagues' earlier observations. On Jan. 30, 1933, the embassy in Berlin sent out a telegram reporting on the appointment of Hitler and the new cabinet, emphasizing the "reactionary and monarchist influence" at work in the new government. At first, many diplomats believed that this conservative containment of Hitler would ensure that the government's agenda would not be determined by the National Socialists' radical ideology.
It didn’t take long for those observers to change their tune. Der Spiegel continues:
But, in subsequent weeks, the regime began to unleash its campaign of violence and terror -- on a governmental and administrative level as well as on the street. It was only once foreign consulates started seeing rising demand for immigration visas and a growing exodus to neighboring countries that the significance of the events of January 30 began to sink in.
About five and a half years later, Europe’s leaders gathered to bless Germany’s annexation of the largely ethnically German “Sudetenland” of Czechoslovakia (not invited: Czechoslovakia). Less than a year after that Germany invaded Poland and World War II began. The world would never be the same.
Today, of course, despite Merkel’s invocation of Hitler as ultimate cautionary tale, comparisons of him to present day leaders and events are generally frowned upon.