As both night and day are useful, as both rest and action are necessary, so both thinking and imagination have their place in our life. For instance, if a poet used his will to direct his imagination it would become a thought and would become rigid. The natural thing for a poet is to let his mind float into space; and whatever it happens to touch to let his heart express it, and then what is expressed is an inspiration. But when a person has to attend to a business affair he must not let his heart float in the air; he must think of the things of the earth, and think about figures very carefully.