The clash with the generals is a risky move for a legendarily cautious man. How far the Brotherhood is willing to push the military will be clearer in coming days. Coming together again with the young activists, it flexed its muscle by mobilizing 200,000 or so into Tahrir Square on Tuesday at a few hours’ notice. Friday’s protests were as big.

Yet prudence elbows in on Mr. Al Shater’s uncharacteristic belligerence. The Brotherhood isn’t mobilizing trade unions. While crowds in Tahrir are a nuisance, national strikes could paralyze a weak economy and harm business elites, including the military. Mr. Al Shater repeatedly invokes variations of “we don’t want a collision” with the regime—be it to reform the security services, overhaul the command-style economy or resolve this conflict. Egypt can only be changed “gradually,” he says. “It will take two, three, four, five years.” Put this way, his red lines get blurrier.

“Politics is the art of the possible,” he says. “Don’t expect us to look for a collision or use violence. Our method is the peaceful way, relying on the basics of the political game. We tried dialogue and we will try dialogue now and in the future.”…

If handed executive power, will the Brotherhood try to Islamicize Egypt from the top down? “Who says this doesn’t know the nature of Islam,” shoots back Mr. Al Shater. “There’s a phrase in Islam: ‘You should not force anything in religion.'” These issues can be handled “in a very democratic way” and safeguard free choices “in personal life.” So it would seem that under a Brotherhood government, beer or bikinis may be banned by an elected parliament but enjoyed in the privacy of an Egyptian’s home.