If psychology is a science, it is no longer a thing of guesses or theories, but is a grouping of confirmed facts about the mind, facts proved in the psychology laboratory even as chemical facts are demonstrated in the chemical laboratory. Wherein psychology departs from facts which can be proved by actual experience or by accurate tests, it becomes metaphysics, and is beyond the realm of science; for metaphysics deals with the realities of the supermind, or the soul, and its relations to life, and death, and God. Physics, chemistry, biology have all in their day been merely speculative. They were bodies of theory which might prove true or might not. When they worked, by actually being tried out, they became bodies of accepted facts, and are today called sciences. In the same way, the laws of the working of the mind have been tested, and a body of assured facts about it has taken its place with other sciences.
It must be admitted that no psychologist is willing to stop with the known and proved, but, when he has presented that, dips into the fascinations of the yet unknown, and works with promising theory, which tomorrow may prove to be science also.