Timber!

In his book How Shall We Live? Francis Schaefer vividly illustrates the end of a faulty world-view...

A culture or an individual with a weak base can stand only when the pressure on it is not too great. As an illustration, let us think of a Roman bridge. The Romans built little humpbacked bridges over many of the streams of Europe. People and wagons went over these structures safely for centuries, for two millennia. But if people today drove heavenly loaded trucks over these bridges, they would break.

It is this way with the lives and value systems of individuals and cultures when they have nothing stronger to build on than their own limitedness, their own finiteness. They can stand when the pressures are not too great, but when pressures mount, if they do not have a sufficient base, they will crash--just like a Roman bridge would cave in under the wight of a modern six-wheeled truck.