Chapter II, of Mary Shelley's Frankenstein, offers readers an in-depth, and specific, reason behind Victor's foreshadowed obsession/interest with science.
When I was about fifteen years old we had retired to our house near Belrive, when we witnessed a most violent and terrible thunderstorm. It advanced from behind the mountains of Jura; and the thunder burst at once with frightful loudness from various quarters of the heavens. I remained, while the storm lasted, watching its progress with curiosity and delight. As I stood at the door, on a sudden I beheld a stream of fire issue from an old and beautiful oak which stood about twenty yards from our house; and so soon as the dazzling light vanished, the oak had disappeared, and nothing remained but a blasted stump. When we visited it the next morning, we found the tree shattered in a singular manner. It was not splintered by the shock, but entirely reduced to thin ribands of wood. I never beheld anything so utterly destroyed.
Victor's description of the storm, prior to the lightening strike to the tree, brought about feelings of "curiosity and delight." Victor's shock at the complete destruction of the tree sparks his interest in science.
Soon after, Victor began to immerse himself in the studies relating to science.
All that he said threw greatly into the shade Cornelius Agrippa, Albertus Magnus, and Paracelsus, the lords of my imagination; but by some fatality the overthrow of these men disinclined me to pursue my accustomed studies. It seemed to me as if nothing would or could ever be known.
Specifically, Victor's dissatisfaction with the previous knowledge of the scientists, Victor's obsession is foreshadowed. Victor, almost disillusioned, begins to study all aspects of science and mathematics.
In this mood of mind I betook myself to the mathematics, and the branches of study appertaining to that science, as being built upon secure foundations, and so worthy of my consideration.
Victor's obsession is later divulged as his own health begins to deteriorate as he throws himself into his work. His self-exile alienates him from his family and his friends, his body begins to show signs of extreme stress, and his mind begins to falter. Perhaps no other statement is more telling, regarding his imminent obsession, than his final recollection made in chapter two:
It was a strong effort of the spirit of good; but it was ineffectual. Destiny was too potent, and her immutable laws had decreed my utter and terrible destruction.