The quote from Vladimir Nabokov's "Lolita" suggests that the idea of executing a flawless crime, particularly murder, is beyond human capability. No matter how meticulously a plan is crafted, there is always a risk of unforeseen variables and human error that can thwart it. This reflects a broader theme about human limitations in controlling life and death.

Additionally, the mention of chance implies that random events or circumstances can sometimes lead to outcomes that seem perfect or unintentional. This highlights the unpredictability of fate and how sometimes, it may be external factors rather than deliberate actions that lead to significant consequences, including murder.