The quote from Arthur Conan Doyle's "The Sign of Four" highlights the paradox of human behavior. While it is difficult to predict the actions and motivations of an individual person due to their unique circumstances and complexities, when observing larger groups, patterns and probabilities emerge. This concept suggests that collective human behavior can often be analyzed and understood through statistical or mathematical principles.

This idea has implications in various fields, including sociology, psychology, and even criminology, suggesting that while individual cases may be puzzling, broader trends can help in making predictions about future behaviors. Understanding the group dynamics can provide insight into societal norms and tendencies, reinforcing the idea that humans, when viewed as part of a collective, can be quantified in their interactions and outcomes.