Victor's interest is first brought up in chapter two of Frankenstein. From the time he was very little, Victor was enthralled with science. He describes himself as always having an interest in science (which denotes he was interested in science at a very young age). Victor's own words tell readers of his love of science:
It was the secrets of heaven and earth that I desired to learn; and whether it was the outward substance of things, or the inner spirit of nature and the mysterious soul of man that occupied me, still my inquiries were directed to the metaphysical or, in it highest sense, the physical secrets of the world.
Later in the chapter, Victor recalls a violent thunderstorm which came upon his home when he was around fifteen years of age. It was one bolt of lightening which solidified Victor's interest in science forever (at least in his mind for forever at that point in his life).
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.
Victor recalls that he had never seen something destroyed like the tree which the lightening bolt hit. This event alone insured Victor's future obsession with science.
The use of the lightening imagery traverses the novel. Many times, Victor sees the creature in a flash of lightening. At one point, Victor compares the speed of the creature to that of a bolt of lightening.
The constant recurring image of the lightening, which solidified Victor's interest in science, is important because it serves as a reminder to Victor (while unacknowledged) and the reader (in critical analysis) the impact the lightening has the novel's entirety.