Kennedy argues that the strength of a political system is best judged under difficult conditions rather than during periods of stability. When circumstances are favourable, many forms of government may appear effective because they are not being tested by severe economic, military or political pressures.

The important test, in Kennedy’s view, comes when a system faces a crisis and must continue to make decisions, retain public confidence and respond effectively without breaking down. In Why England Slept, this observation forms part of a wider discussion of how governments respond to external threats and national emergencies. The quotation therefore focuses less on the abstract merits of particular constitutional arrangements than on their practical resilience. Its broader point is that institutions demonstrate their durability through their capacity to function under pressure, when weaknesses that remain hidden in ordinary circumstances are more likely to become visible.