Egypt has been a powder keg many times in the past five millennia, and it may have exploded again Friday, with the fuse lit by President Mohammed Morsi's apparent attempt to assume absolute power in the Land of the Pharoahs Thursday.

Tens of thousands of demonstrators gathered in Cairo's Tahrir Square to protest Morsi's trying to make himself accountable to nobody in the executive, judicial, or legislative branches of what is nominally a republic, Ahram Online reported.

Similar demonstrations in Tahrir Square were keys to the successful Egyptian Revolution of 2011. That revolution led directly to the exit of another autocrat, Hosni Mubarak, who was ousted as president last year, and indirectly to the entrance of Morsi, who was elected as president as the candidate of the Muslim Brotherhood's Freedom and Justice Party this year.

Meanwhile, hundreds of Morsi's backers rallied outside the presidential palace in Cairo to express support for the Egyptian leader, who took office June 30, Al Jazeera reported.

Protests turned violent in Alexandria, Port Said, and Suez, as well as Cairo. Since Morsi's purported power grab, they have been complemented by attacks on Freedom and Justice Party offices in five cities, Al Jazeera said.

Critics of Morsi's move Thursday claim the president has awarded himself dictatorial powers because his new rules stipulate that no presidential decision made since he took office can be appealed, Ahram Online reported.

They also contend Morsi's declaration shields both houses of the Islamist-dominated Parliament -- the People's Assembly (the lower house) and the Shura Council (the upper house) -- from possible dissolution by pending court orders, Ahram Online said.

One of many chants by Cairo demonstrators Friday struck a familiar chord, as it conflated Egypt's past and present autocratic presidents, "Down with Mohamed Morsi Mubarak."

Protests of Morsi's moves were not limited to the Arab Street. Mohamed ElBaradei -- who was the director general of the International Atomic Energy Agency when both he and the IAEA were jointly awarded the Nobel Peace Prize in 2005 -- took to Twitter Thursday and Friday to register his own.

On the former day, ElBaradei tweeted: "Morsi today usurped all state powers & appointed himself Egypt's new pharaoh. A major blow to the revolution that cld have dire consequences."

On the latter day, he tweeted, "In light of staunch & broad opposition, Morsi should rescind his 'power grab' constitutional declaration b4 situation gets out of hand."

Which is eminently good advice whenever the fuse of a powder keg has been lit.