How we cite our quotes:
All was again silent, but his words rang in my ears. I burned with rage to pursue the murderer of my peace and precipitate him into the ocean. I walked up and down my room hastily and perturbed, while my imagination conjured up a thousand images to torment and sting me. Why had I not followed him and closed with him in mortal strife? But I had suffered him to depart, and he had directed his course towards the mainland. I shuddered to think who might be the next victim sacrificed to his insatiate revenge. (20.16)
Too bad Victor isn't the next sacrifice—but then, the book would be even shorter than it already is. We're still not getting the feeling that Victor understands what's going on, since the word "sacrifice" seems to absolve him of any responsibility.
I desired that I might pass my life on that barren rock, wearily, it is true, but uninterrupted by any sudden shock of misery. If I returned, it was to be sacrificed or to see those whom I most loved die under the grasp of a daemon whom I had myself created. (20.18)
Wouldn't living alone on a barren rock be a kind of sacrifice, too? (And maybe worse than being killed by the monster?) Victor really is in a tricky position, here.
"I am not mad," I cried energetically; "the sun and the heavens, who have viewed my operations, can bear witness of my truth. I am the assassin of those most innocent victims; they died by my machinations. A thousand times would I have shed my own blood, drop by drop, to have saved their lives; but I could not, my father, indeed I could not sacrifice the whole human race." (22.6)
Let's work through this logic: Victor is sacrificing his family by refusing to make Mrs. Monster, because he can't bear to sacrifice the whole human race by not making her. Of course, he could just try being a dad to his creation—but apparently that's out of the question.