What does 'the elixir of life is a chimera' mean?

In this situation, Victor's professor is telling him that all of the books he has been reading and researching are imaginary. Shelley later explains how men like Agrippa were merely fools. It is the chemists who discover the wonders of reality. The significance of this Word is that although most people believe things like the elixir of life and the philosopher's stone to be made up, Victor still has faith and "dreams . . .undisturbed by reality. . ."

His imagination is what made him able to do what he did (creating a monster).