In the globalized, postmodern world, the production of encounters and crashes between dissimilar cultures, ways of life, and systems of values has drastically increased in number. More and more frequently, they originate harsh conflicts, exhibiting the existence of alternative and apparently incompatible ways of living and thinking—culturally, religiously, economically and politically speaking. In this context, words as tolerance and intolerance have been put at the heart of the political debate. However, what is the real meaning of these political concepts? Why did they originate and how did the developed over time? Do they still represent a valid resource for comprehending our current societies and dealing with them? Through the different voices of several scholars in the humanities, this book traces the history of tolerance since the wars of religion to the contemporary age, combining the historical reconstruction with a theoretical and critical analysis of the idea and practice of tolerance in different epochs and places. The obstacle course depicted here reveals the constitutive fragility of this concept that, however, cannot be totally dismissed from our political vocabulary.