The shared understanding that is society, is founded upon a set of shared beliefs about right and wrong. This is the sanity of the society, which is expressed and maintained by tradition.
Hence, the moment a society stops upholding its traditions, is the moment its understanding starts to lose its sanity. And the moment this collapse begins is when a society violently replaces the traditional rule of a monarch with popular rule. This is why Arnold Toynbee noted in "A study Of History", that the decline of every civilisation begins with a class war that displaces the traditional rule of a monarch.
Society's Mind
The mind, or thoughts, of the shared understanding, is the exchange of opinions. With popular opinions winning communal action while unpopular opinions are ignored. However, while tradition demands the courts penalize expressions of obscenity, treason, heresy, libel or slander, any other restraint must be seen as tyranny, which is compulsory insanity.