This article is not comprehensive. It aims at encouraging all teachers of mathematics "to look behind the subject matter" and to probe what educational values it contains. More examples can easily be found. Suffice it to say that when Pythagoras proved his famous theorem, mankind "discovered" that the square root of 2 is an irrational number. The fact that you cannot write its exact value as a decimal fraction gave people at that time the feeling that they had "lost control of their fate". "Friendly" and "perfect" numbers were created at that time to ward off the doom. Similar feelings of despair followed the recognition that the Earth is not the center of the universe and the use of the atom bomb. All three events in the history of science even led to mass suicides. The examples given above call upon all educators to use the subject matter to enrich social understanding and to help youngsters to build a healthier society.