But in the meantime, as a temporary measure, I hold what I call the doctrine of the jig-saw puzzle. That is: this remarkable occurrence, and that, and the other may be, and usually are, of no significance. Coincidence and chance and unsearchable causes will now and again make clouds that are undeniable fiery dragons, and potatoes that resemble eminent statesmen exactly and minutely in every feature, and rocks that are like eagles and lions. All this is nothing; it is when you get your set of odd shapes and find that they fit into one another, and at last that they are but parts of a large design; it is then that research grows interesting and indeed amazing, it is then that one queer form confirms the other, that the whole plan displayed justifies, corroborates, explains each separate piece.