"A thousand years may scare form a state. An hour may lay it in ruins"

This quote by Lord Byron implies that it can take a long time to build something fantastic like a state or civilization, but it can be destroyed in a brief quantity of time. The concept is that the hard work and devotion of many people building something can be reversed in a flash by a disaster or dispute. This recommends the fragility of greatness and the value of sustained effort and vigilance in maintaining what has actually been constructed over time.