Sometimes... the most important quality an architect can possess is optimism. For example, it took 12 years for the Jewish Museum I designed in Berlin to finally open to the public. A few hours later it had to close. The date: Tuesday, Sept. 11, 2001. That jarring confluence of events not only predated but also presaged my role in rebuilding ground zero. And the memories of what we went through in Berlin give me confidence that we will succeed in New York as well. When I won the museum competition, Berliners were divided between those who felt my design would...