What is a universal truth in the book Frankenstein?

One universal truth from Frankenstein is: If you build a monster, it will kill you. This is probably not the most common "truth" from the novel, however it is the one on which so much Science Fiction has been based since Mary Shelly published it. Hence, the Frankenstein Syndrome of much of modern science fiction. One example of this is a variant of it in the movie, I Am Legend. Man creates virus with the intent of improving the human race (or the standard of living), virus changes man into a monster, monster kills man.