It turned out that the pope has decided not to give the speech at the Sapienza University in Rome, after the protests a bunch of professors (namely, 63 out of approx. thirty-five hundreds) angry at one of his speeches in the nineties, when he apparently said that the roman catholic church at Galileo's age was more rational than Galileo himself, set a fire within the students community.
I will leave my thoughts on the so-called "bad teachers"/"cattivi maestri" apart. At the same time, I am gonna attach a new testament abstract, i think it would fit to the 63...
From the Letter of James
Not many of you should become teachers, my brothers, for you realize that we will be judged more strictly, for we all fall short in many respects. If anyone does not fall short in speech, he is a perfect man, able to bridle his whole body also. If we put bits into the mouths of horses to make them obey us, we also guide their whole bodies. It is the same with ships: even though they are so large and driven by fierce winds, they are steered by a very small rudder wherever the pilot's inclination wishes. In the same way the tongue is a small member and yet has great pretensions. Consider how small a fire can set a huge forest ablaze. The tongue is also a fire. … With it we bless the Lord and Father, and with it we curse human beings who are made in the likeness of God. From the same mouth come blessing and cursing. … And the fruit of righteousness is sown in peace for those who cultivate peace.