(CBS News) JOHANNESBURG -- One of the giants of the 20th century, Nelson Mandela, is back in the hospital Thursday for the third time in four months.
Mandela, 94, spent 27 years in jail as a political prisoner before he unified South Africa without civil war, won the Nobel Peace Prize and became the country's first black president.
Watch: Nelson Mandela responding well to treatment, below.
On Wednesday, Mandela was having difficulty breathing, suffering from a recurring lung infection. At about 11 p.m. Wednesday night, doctors determined that he needed to go to the hospital, since his temperature had spiked and they couldn't bring it down.
Mandela has round-the-clock medical care -- his home is a virtual hospital -- so for doctors to determine he needed to go to the hospital at midnight, it obviously raised concerns about the gravity of the situation.
He spent the night at the hospital, but we understand that his condition has stabilized. He is responding well to treatment, he sat up, he ate lunch and he is talking.
Watch: Obama says he's "deeply concerned" about Nelson Mandela's health, below.
During his time in prison, Mandela contracted tuberculosis. He worked in the lime quarries, and this respiratory infection has its roots there. It has grown increasingly problematic as the president becomes frailer.
The time between Mandela's hospitalizations has grown increasingly shorter -- just 17 days since the last one. In that instance, he was also suffering from a respiratory infection.