In my mind, the overwhelming lessons being taught would consist of the limitations of scientific progress. Victor's embodiment of scientific zeal helps to bring to light how intense the process of scientific inquiry can be and how disastrous its results can be if not properly examined. At the same time, I think that the lesson about ensuring that there is accountability in scientific progress is critical. When confronted with the hideous nature of his creation, Victor abdicates responsibility and flees. In the end, if all scientific authors did this, chaos would result. The lesson of scientific accountability and the need to establish responsibility for what is done in the name of science is of critical importance in any lessons for present and future.
At the time that Mary Shelley created the book Frankenstein the idea of using body parts to replace other parts of a human was unheard of. People were mostly speculative about what medical advances the future would hold and in some places the procedure of bleeding was still used to treat infection or misunderstood diseases.
Modern science has been developing better and better skills at harvesting and transplanting organs into human beings. What had started with putting a baboon heart in infant baby Faye in Loma Linda, California, has now arrived at the ability of mankind to be able to have procedures such as heart, kidney, and lung transplants, and even fingers, toes, and arms reattached. Now the possibility of a person being cloned has neared the probability stage.
If the book teaches us anything it is to be careful what actions we take ethically in regards to human beings and their lives. Science has advanced farther than our legal abilities can solve the conflicts that have arisen from the procedures. The future may well lead mankind into greater and more challenging ethical issues and the reality that one is dealing with a real human who has feelings, needs, and opinions needs to be taken into careful consideration and be ethically challenged before we go to far.