Well, just as history offers a plethora of "lessons" which contending parties can select for themselves in a self-serving way in any dispute over policy, there are many "principals" out there which can be called upon with ease to rationalize almost any action.
The political struggles in Europe and within the key member states are very interesting on several levels. Germany went through its own mini crisis and recovery over a decade ago as Chancelloe Schroeder (gasp!) championed some restrictions on social welfare payments and relaxation of labor market restrictions to correct then sclerotic economic growth and contain the growth of government expenses. They also got through the enormous costs associated with the wealth transfers after reunification. With that in mind I can readily understand the resistence of many Germans to merely bailing out those who regard the abandonment of unrealistic illusions and life on borrowed money as trials too difficult to bear.
On another level, many EUROZONE states (Italy comes to mind) have failed to grasp the evident fact that the common currency makes it impossible for them to avoid political conflicts through mere devaluation of their currency - new behaviors are required and that requirement comes inescapably with the benefits of the common currency.
Finally the several decades of rather amazing European progress in the creation of first a trade union and then moving on to quasi economic and Political union - all without directly confronting some key sovereignty issues - has likely come to an end. It isn't so much a failure as it is the end of an extended period of defying the odds while moving by unresolved core political issues. The piper must eventually be paid.