Remorse extinguished every hope. I had been the author of unalterable evils, and I lived in daily fear lest the monster whom I had created should perpetrate some new wickedness.
In this quote from Chapter 9, Victor admits to himself and the reader that he bears some of the blame for the murders the monster has committed. He goes so far as to call himself the "author of unalterable evils," declaring himself responsible for the terrible tragedies of the last few chapters. He had also held himself accountable in Chapter 8, calling himself the "true murderer" and William and Justine "the first hapless victims to my unhallowed arts." While the fact that he continues in Chapter 9 to recognize himself as the cause of great misery might suggest that his character is undergoing genuine growth, a truer test of whether he has learned from his mistakes will be if his damaging behavior ceases going forward.
Sometimes I could cope with the sullen despair that overwhelmed me, but sometimes the whirlwind passions of my soul drove me to seek, by bodily exercise and by change of place, some relief from my intolerable sensations. It was during an access of this kind that I suddenly left my home, and bending my steps towards the near Alpine valleys, sought in the magnificence, the eternity of such scenes, to forget myself and my ephemeral, because human, sorrows.
In the second half of Chapter 9, Victor explains that to escape the despair that haunts him after Justine and William's deaths, he often goes on long hikes through the Alpine valleys and mountains. The magnificence of the natural world soothes him and gives him relief (albeit fleeting) from his unbearable grief; during one journey, he says, "The weight upon my spirit was sensibly lightened as I plunged yet deeper in the ravine of Arve." When he immerses himself in nature, he is able to temporarily experience peace, or at least "the greatest consolation that [he] was capable of receiving."
The explanation of these lines in Quotes by Character: Victor Frankenstein discusses another aspect of the quote—how Victor taking his love of nature too far leads to bad outcomes.
Immense glaciers approached the road; I heard the rumbling thunder of the falling avalanche and marked the smoke of its passage. Mont Blanc, the supreme and magnificent Mont Blanc, raised itself from the surrounding aiguilles, and its tremendous dôme overlooked the valley.
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 recognised, reminded me of days gone by, and were associated with the lighthearted gaiety of boyhood. The very winds whispered in soothing accents, and maternal Nature bade me weep no more.
This quote from near the end of Chapter 9 captures Victor’s feelings of calm and relief as he hikes in the Swiss Alps around Mont Blanc and is reminded of the peaceful days of his childhood. These will be the last moments of calm he will feel prior to his upcoming encounter with the monster in Chapter 10. You can read more about this quote in Quotes by Setting: The Alps and the Arctic Ocean.