Reasonableness at last. That was the general reaction Wednesday to the news that Iranian President Hassan Rouhani appeared to acknowledge and condemn the Holocaust during an interview this week with CNN's Christiane Amanpour. Previous President Mahmoud Ahmadinejad had rarely missed an opportunity to call the Nazi genocide of six million Jews a "myth." But Mr. Rouhani has adopted a more tempered tone, and the world longs to see him as someone with whom "we can do business together," as Margaret Thatcher once said about Mikhail Gorbachev.

One...