Not less valuable is the power of imaging in the study of history. Many details are worthless and meaningless until the imagination weaves them into a fabric in which their relations and significance become apparent. So far as the trend of history is concerned, it would have mattered very little if the name of the ship in which the Pilgrim fathers sailed had been Aprilshower instead of Mayflower, if the number of passengers had been one hundred and one instead of exactly one hundred, if they had landed at some place other than Plymouth Rock. Their coming, their compact, their religious life and purposes were of chief importance. Details help to fill out the mental picture of their voyage, landing, and settlement. They throw a halo of interest around the central event, or germinal idea. Or, to change the figure, they furnish the scaffolding by means of which the teacher gradually raises the edifice of historical knowledge. After the edifice has been completed the scaffolding may be removed. After the essential or central idea has been grasped and fixed, details like the name of the ship, the number of emigrants, and the exact day of their arrival may be forgotten. The mind can often unload the luggage that is not absolutely needed, and move with more ease and speed into new fields of thought and investigation.
Geometry has been aptly styled eine Augenwissenschaft, “a science of the eye” (the last word being used not as the object with which the science deals, but as the means by which its ideas are acquired). The line drawn upon the black-board has breadth, and is not at all a mathematical line. Through the eye it serves to suggest the line which has length without breadth or thickness. Progress in solid geometry is impossible if the mind does not image or conceive the volumes of three dimensions indicated by the drawings on a surface which has but two dimensions. In arithmetic many of the business transactions upon which the problems are based have not come into the experience of the child, but must be evolved by appeals to the imagination if the solutions are to be brought within easy reach of the understanding. The power of combining images into new forms aids greatly in the construction of apparatus and in the making of experiments. It helps the scientist to evolve his theories and hypotheses. It is the faculty by which man becomes a creator in science, art, literature, and philosophy.