What does the author mean when he writes that “the rules of civil society must be adapted to the general constitution of things”? how does this phrase him gain authority for his perspective?

The american anti-slavery society (aass) (1833–1870) was an abolitionist society founded by william lloyd garrison, and arthur tappan. frederick douglass, an escaped slave, was a key leader of this society who often spoke at its meetings.

One of the things that allowed native americans in mexico to settle cities larger than those in areas to the north was "b. the development of cities that were built by an earlier civilizations," since mexico had been the home of some of the world's most advanced civilizations before the columbian invasion

Sure, what are the questions ?