Idle youths with no income and little chance of a productive livelihood is a dangerousmix, and one that is very capable of raising the specter of a full social breakdown.
Free capital movement and pegged exchange rates are a dangerousmix (unless the currency is fixed under a currency-board arrangement as in Hong Kong, where all local currency must be fully backed by American dollars).
The Habsburg capital is on the cusp of modernity, its cosmopolitan mix of nationalities, and the dangerous new notions propagated by Sigmund Freud are evocatively pictured.
Britain's approach to tackling domestic extremism has sought to mix vigilance with openness, on the principle that militants are least dangerous in places where they and their followers can be closely watched.