In concurrence with post #3, Victor's isolation is pivotal to this demise. In Mary Shelley's time, friendship among men was highly lauded, perceived as an elevated love; its importance significant. As a foil to Victor, Henry Clerval is the counterbalance to Victor. When Victor isolates himself from his friends and family, he, then, loses this sense of balance between science and soul.
In another novel, Notre Dame de Paris (The Hunchback of Notre Dame), Claude Frollo, the Archdeacon of Notre Dame becomes obsessed with alchemy and the scientific efforts to create gold. A friend comes to him and explains the danger of Frollo's scientific search, telling him that it is like the spider's web that a fly enters: there is no escape, no backing out. Victor Frankenstein goes down a path that eliminates his humanity, a humanity that Henry Clerval fostered for him as friend.
I think it's when Victor "decided" that the pursuit of science was more important than his realtionships with his friends/fiancee, and when he isolated himself from all human companionship and began his great experiment. Part of the general thinking of Romanticism is that reason is not the only path to truth, that science can only tell us how to do things and not why (cf. "The Birthmark," Hawthorne"), and that intuition is just as important a path to "truth" as tuition.
Victor's intentions were good; conquering death, giving the gift of life to many/all, is certainly a goal shared by many scientists. But Victor's isolation cut him off from all those who might have tempered his enthusiasm, who might have reminded him that love is more important that just continuing life, and that if you are going to create life, you have an obligation to love that life, no matter how imperfect it turns out to be.
Certainly the pivotal moment in Victor's life was when he elected to allow his ego to take the best of him and, instead of admiring the sciences of physics, biology, and chemistry as fields of study and perhaps elements of genius, he allowed his weakness for ambition and power to switch his love for science to love for self-grandiosity.
It was this same desire to be something higher than himself what drove his insane idea of obtaining a body with dead parts to try to make it come to life. Even further, it was his sick and obsessive nature what basically allowed the supernatural to take place: His ambition was so out of this world that it actually brought the obscure into his action, and manifested.
Thats very true, but would you say we would just assume this from the tone of what he says during his time at Ingolstadt from his studies and when he talks about his interests or is there any specific part of quote that your basing that idea from?