Last week, rumors began to surface that former Iranian President Mahmoud Ahmadinejad would not run for president in the country's 2017 elections. Today, he confirmed those rumors. In a letter spread widely in Iranian media, Ahmadinejad dispelled any notion that he would again occupy the highest elected office in Iran, though he described himself as a "soldier of the revolution and servant of the people." The letter came after a tense meeting with Supreme Leader Ayatollah Ali Khamenei, who apparently had urged Ahmadinejad to forgo the election. In that way, the letter is a show of deference to the Iranian government's machinery, controlled as it is by Khamenei, and it puts on display the full power of the clerical establishment, which has long opposed the irreverence in which Ahmadinejad held its leaders. But still, coming from one of Iran's most bombastic and still-popular political leaders, the letter likely is a...