In Frankenstein, Victor is tormented by the thought that he is responsible for the murders committed by the monster. His feelings of guilt haunt him and spur his revenge against his creation. The only respite for Victor from the cruelties of science and civilization is nature.
Observe this quote from pg. 79 of my book:
A tingling long-lost sense of pleasure often came across me during this journey. Some turn in the road, some new object suddenly perceived and recognized, reminded me of days gone by, and were associated with the light-hearted gaiety of boyhood. The very winds whispered in soothing accents, and maternal Nature bade me weep no more. Then again the kindly influence ceased to act -- I found myself fettered again to grief and indulging in all the misery of reflection.
As you know, the Romantics revered nature. Nature was their haven from the heartless world. Nature's sublime beauty was divine, and they retreated to it whenever they were troubled or needed inspiration.