What does Victor mean when he says, "'Learn from me, if not by my precepts, at least by my example, how dangerous is the acquirement of knowledge and how much happier that man is who believes his native town to be the world, than he who aspires to become greater than his nature will allow,'" in chapter 4 of Frankenstein?
Victor Frankenstein certainly shows that he is a smart man when he states the following in Chapter Four of Mary Shelley's novel Frankenstein:
Learn from me, if not by my precepts, at least by my example, how dangerous is the acquirement of knowledge and how much happier that man is who believes his native town to be the world, than he who aspires to become greater than his nature will allow.
What Victor is saying here is that it he hopes that people use his mistakes as an example. Victor knows that knowledge can be dangerous at times. By this, he refers to the fact that sometimes "ignorance is bliss" based upon the fact that, sometimes, knowledge does more harm than good.
In the second part of the quote, Victor is admitting that people who look too far beyond their own capabilities are wrong. For Victor, the reference to a person's native town shows that a person should recognize and accept their own limitations. By looking at the entirety of the world as one's background, one can end up causing more, again, harm than good.
In short, people should be happy with what they have. Outside of that, the quest becomes too burdensome, too demanding, and too dangerous. Victor, in the quote, is simply giving out some amazing advice--know your limitations and abide by them.
Victor has tried to play God, has tried -- in fact -- to be like the Titan Prometheus, who stepped in to help his brother Epimetheus create humankind when Epimetheus mistakenly made all of the animals first, giving them all the "good" qualities (i.e. thick hide or fur to protect them, sharp teeth and claws to help them to eat, etc.). Prometheus had to get creative to come up with qualities that would help us to be the best: he made us walk upright like the gods, and he gave us the fire that would help defend us from the cold and help us to cook the meat that our teeth could not otherwise chew. Victor has tried to create a new human species, a species that he expected would "bless him as its Creator." He wanted to perfect something that he saw as imperfect -- human frailty and fragility -- but he learned, too late, that human beings are not meant to create in this way: his creation turns out to be horrifying, perhaps in part because it was made by an imperfect (i.e. human) creator. Thus, when Victor describes the dangers of striving to be "'greater than [one's] nature will allow,'" he also refers to the dangers of a human being who tries to play God. Victor's hubris results in tragedy for so many people, including himself and the individual he creates.