For example, consider the Battle of Waterloo. This battle resulted in the defeat of Napoleon, and in a constitution of our actual world grounded upon that defeat. But the abstract notions, expressing the possibility of another course of history which would have followed upon his victory, are relevant to the facts which actually happened. We may not think it of practical importance that imaginative historians should dwell upon such hypothetical alternatives. But we confess their relevance in thinking about them at all, even to the extent of dismissing them. But some imaginative writers do not dismiss such ideas. Thus, in our actual world of today, there is a penumbra of eternal objects, constituted by relevance to the Battle of Waterloo. Some people do admit elements from this penumbral complex into effective feeling, and others wholly exclude them. Some are conscious of this internal decision of admission or rejection; for others the ideas float into their minds as day-dreams without consciousness of deliberate decision; for others, their emotional tone, of gratification or regret, of friendliness or hatred, is obscurely influenced by this penumbra of alternatives, without any conscious analysis of its content. The elements of this penumbra are propositional prehensions, and not pure conceptual prehensions; for their implication of the particular nexus which is the Battle of Waterloo is an essential factor.
Thus an element in this penumbral complex is what is termed a 'proposition.' A proposition is a new kind of entity. It is a hybrid between pure potentialities and actualities. (185-186)