The outcome of the impending battle between Egypt's first civilian president and its powerful generals will redraw the country's political landscape after 60 years of de facto military rule.
If Morsi succeeds, the Muslim Brotherhood will likely be emboldened to press ahead with realizing the longtime goal of making Egypt an Islamic state. Otherwise the military - which has been reluctant to give up the power it assumed after Hosni Mubarak's ouster - will continue its stranglehold on the country for years, maybe decades, to come.
For Egypt's estimated 82 million people, the prospect of a continuing battle between the military and the Brotherhood, the country's largest political group, will only prolong the political instability that has rocked their nation since Mubarak's ouster last year. Egyptians have seen the initial euphoria following the revolution turn into a wave of pessimism amid a declining economy, rising crime and a seemingly endless wave of protests, strikes and sit-ins.
The yearning for stability was expressed by two prominent figures. Nobel Peace Laureate Mohamed ElBaradei, also Egypt's top pro-democracy advocate, tweeted that it was time to resolve the thorny issues of the new constitution, the president's powers and legislation. "Now, the time for building has come, to achieve the revolution's goals," he said.
Gamal Eid, a well-known rights lawyer and activist, saw in Morsi's inauguration the chance for someone in power to be held accountable. "Now the ball is in the president's court after he became the first elected president of Egypt. Now we can hold him accountable either with or without authorities."
Both sides - Morsi and the military - made a show of unity during the inauguration ceremonies that began with the 60-year-old U.S.-trained engineer being sworn in at the Supreme Constitutional Court, then making an address a few hours later at Cairo University as the ruling generals applauded politely.
Morsi repeated his oath of office in the university's gigantic lecture hall and lavishly praised the military council, which had promised to hand over power to a civilian government by July 1 but pushed through a series of decrees this month that stripped the president of significant powers before doing so.
The decrees gave the military legislative authority after the parliament was dissolved by court order as well as control over the process of drafting a permanent constitution. It also retained its influence on key domestic and foreign policy issues.
"The armed forces are the shield and sword of the nation," Morsi told an audience of several thousand people, including many members of the disbanded Islamist-dominated parliament.
"I pledge before God that I will safeguard that institution, soldiers and commanders, raise its prestige and support it with all the powers available to me so it can be stronger," he added.
But Morsi later appeared to urge the military to hand over all powers to his elected administration.
"The (ruling) Supreme Council of the Armed Forces has honored its promise not to be a substitute for the popular will and the elected institutions will now return to carry out their duties as the glorious Egyptian army returns to being devoted to its mission of defending the nation's borders and security," he said.
Military ruler Field Marshal Hussein Tantawi's arrival at the hall was greeted by conflicting chants of "the army and the people are one hand" and "down with military rule." He and Gen. Sami Anan, the powerful chief of staff, showed no emotion during Morsi's address, but did occasionally clap.
The military already has won the first round, forcing Morsi to take his official oath of office before the court because there is no parliament, the traditional venue for inaugurations.
The Supreme Constitutional Court is packed with judges appointed by Mubarak before his ouster and it is the same tribunal that ruled two weeks ago that a third of parliament's members were elected illegally. Armed with that verdict, the military disbanded the chamber.
The Brotherhood has questioned the legality of the military's decree and called for the reinstatement of the legislature in which it controlled just under half the seats. Some of the group's leaders wanted Morsi to be sworn in before members of the dissolved legislature, but the idea was shelved over fears it could unleash a crackdown by the military.
Instead Morsi read an informal oath of office during a rousing speech before tens of thousands of supporters Friday in Cairo's Tahrir Square, the epicenter of the revolution.
A court official who was present at Saturday's swear-in ceremony said Morsi insisted that the proceedings not be shown live on television, preferring that they be recorded and aired after his university address. The judges refused, warning him of legal repercussions. He eventually backed down but not before the ceremony was delayed by nearly two hours.
The official spoke on condition of anonymity because of the sensitivity of the subject, but Tahani el-Gebaly, one of the court's 18 judges, made similar comments to the state Al-Ahram daily newspaper.
Betraying his anger, Morsi was grim-faced throughout the ceremony, avoiding eye contact with the black-robed judges in the wood-paneled chamber. In a dark blue suit and red tie, he looked straight at the camera rather than the court's chief judge, Farouq Sultan, as he read the oath.
"We aspire to a better tomorrow, a new Egypt and a second republic," Morsi said in a brief address to the judges. The courthouse, whose court is a Nile-side structure built to resemble an ancient Egyptian temple, is next door to the military hospital where Mubarak is being held after his transfer from a prison hospital.
The ousted leader is serving a life sentence for failing to prevent the killing of protesters during the uprising that toppled his regime last year.
"Today, the Egyptian people laid the foundation of a new life - absolute freedom, a genuine democracy and stability," said Morsi after the court ceremony.
Curiously, Morsi made no mention of the Brotherhood's goal of bringing Egypt more in alignment with Islamic teachings in three speeches he delivered on Saturday, with his citation of a handful of Quranic verses the only sign of his political orientation.
He also did not raise the case of the Egyptian-born blind sheik Omar Abdel-Rahman, who is jailed in the U.S. for plotting to blow up New York City landmarks and assassinate Mubarak.
Morsi vowed to work for his release, along with political detainees in Egypt, in Friday's speech at Tahrir Square, but it was unclear if he planned a serious appeal or was responding to populist pressure after seeing a group of protesters with posters of the detainees.
Later at a military ceremony held at a base east of Cairo, Tantawi and Anan saluted Morsi as he arrived and awarded him the "shield of the Armed Forces" - the Egyptian military's highest honor. Morsi also received a 21-gun salute before he and Tantawi addressed the ceremony.
The location of the ceremonies was loaded with symbolism for the Brotherhood, whose members were jailed and suppressed for decades, including during Mubarak's secular rule.
Cairo University was established in 1908 as Egypt's first seat of secular learning but became a stronghold of Islamist student groups in the 1970s. Many of their leaders have gone on to become today's stalwarts of the Brotherhood, Morsi included.
The base, also known as Huckstep camp, houses a military court in which Brotherhood leaders were tried during the Mubarak years.
Hundreds of soldiers and policemen guarded the Supreme Constitutional Court building as Morsi arrived in a small motorcade. Only several hundred supporters gathered outside the court to cheer the new president and, in a departure from the presidential pomp of the Mubarak era, traffic was only briefly halted to allow his motorcade through on the usually busy road linking the city center to southern suburbs.