The speech Pope Benedict XVI would have given at La Sapienza University in Rome today, if the visit had not been cancelled because of anti clerical student protests, made clear he was against imposing faith by authoritarian means, the Vatican said yesterday.

In the speech he asks "What does the Pope have to say at a university? He surely does not need to try and impose faith in an authoritarian way. Faith can only come by free will". He noted that the Pope was "Pastor of the Church", and "following the implicit nature of this pastoral ministry it is my job to keep awake the desire for truth".

The speech was released by the Vatican press office. In it the Pope emphasised the difference between knowledge, which for the ancient philosophers was a source of sadness, and truth, which he said in the Christian view "makes people free".

He said the Gospels were aimed at "putting reason on the path searching for the truth, for what is good, for God." Jesus Christ was "the light that illuminates history and helps find the way towards the future".

Yesterday Catholic university students who attended the Pope's weekly audience shouted their support. "If the Pope won't come to La Sapienza, La Sapienza will come to the Pope," read one banner held by students. Cardinal Camillo Ruini, the Vicar of Rome, asked Italians to come to St. Peter's Square on Sunday to show their backing for the pontiff.

He said the "sad episodes" that forced the Pope to cancel his speech "delivered a very painful blow to the whole city". The protesters at La Sapienza, who included professors and lecturers as well as students, had attacked Benedict's views on science, saying a speech he gave in 1990 justified the Church's heresy trial against Galileo in the 17th century.

However the Italian press criticised the "intolerance" of the protests, with Corriere della Sera running a front page editorial headlined "A defeat for the country". Renato Guarini, the university rector, said the Pope was "a man of culture and great thinker" who should have been allowed to speak.

Opposition to the visit began when a group of 67 academics signed a letter requesting that Professor Guarini withdraw the invitation to the Pope. In the letter, the academics said they opposed the "incongruous" visit by Benedict, whom they accused of being a reactionary and an opponent of free thought and scientific research.