The following study represents an attempt to determine the fundamental difference between poetry and prose and the relation of simple rhythm, or metre, to poetry. The reader should bear in mind that in all branches of science and art distinctions and classifications hold good, as a rule, only in a broad and general way; there are always border-line phenomena that defy classification. For example, we make a general distinction between animal and plant life, and yet of some of the lower forms of life it is difficult to say whether they belong in the one class or in the other. Or again, it is no uncommon thing to hear chemists and physicists dispute regarding the provinces of their respective sciences. And again, rhythm and melody seem to us to be very different things, and yet at bottom they are both rhythm, because differences in pitch depend upon differences in frequency of vibration, and in any melody these vibration frequencies stand in a rhythmical relation to each other. The farther we penetrate into any subject, the more difficult does exact classification become. And so our distinction between poetry and prose must be taken in a rather broad and general way. There are pieces of prose which seem to be highly poetic in nature, and there are poems in which the writer seems to have encroached upon the province of prose. Be this as it may, I believe we can at least say that in this direction lies the field of poetry, in that the field of prose. With this general reservation, then, let us ask the question: What is the essential difference between poetry and prose?