"Probability is expectation founded upon partial knowledge. A perfect acquaintance with all the circumstances affecting the occurrence of an event would change expectation into certainty, and leave nether room nor demand for a theory of probabilities"

In this quote, George Boole is talking about the idea of possibility and how it is based on minimal understanding. He explains that if we had complete understanding of all the factors that influence an event, our expectations would end up being certain and there would be no requirement for a theory of likelihoods. Boole suggests that our understanding of probability is shaped by our understanding of the circumstances surrounding an event. He indicates that the more we know about these scenarios, the more precise our expectations end up being. Ultimately, Boole highlights the significance of understanding and its role in shaping our understanding of likelihood.