In many Islamic countries, the expansion and the radicalization of religious integralism lead to manifestations of violent intolerance which recall episodes from the sixteenth and seventeenth centuries. There has been a new awareness within the whole of humanity of the growth of intolerance towards that which is ‘different’; this is displayed in a multiplicity of attitudes on the part of individuals, of groups and of governments. The concept of tolerance was developed at the beginning of the modern age, but it had a few significant antecedents in the Old World from which modern authors not infrequently draw inspiration. In its simplest and most fundamental form, tolerance consists in recognizing the right of others to be respected as persons and for their identities. The modern political and social values from which international norms have arisen in the field of human rights were first of all formulated in an appeal for tolerance as an essential condition to maintain social order.