an attitude of reserve in regard to this problem. We do not solve this problem; we put it on one side.
And, certainly, we are right to do so. The soul, viewed as a substance—that is, as a something distinct from psychical phenomena, which, while being their cause and support, yet remains inaccessible to our direct means of cognition—is only an hypothesis, and it cannot serve as objective to a science of facts. This would imply a contradiction in terms.
Unfortunately, we must confess that if it be right to relegate to metaphysics the discussion on the concept of the soul, it does not really suffice to purge our minds of all metaphysics; and a person who believes himself to be a simple and strict experimentalist is often a metaphysician without knowing it. These excommunications of metaphysics also seem rather childish at the present day. There is less risk than some years ago in declaring that: “Here metaphysics commence and positive science ends, and I will go no further.” There is even a tendency in modern psychologists to interest themselves in the highest philosophical problems, and to take up a certain position with regard to them.
The second kind of definition is, we have said, that by enumeration. It consists in placing before
