"Locke would have us begin with the study of spirits and go on to that of bodies. This is the method of superstition, prejudice, and error; it is not the method of nature, nor even that of well-ordered reason; it is to learn to see by shutting our eyes. We must have studied bodies long enough before we can form any true idea of spirits, or even suspect that there are such beings. The contrary practice merely puts materialism on a firmer footing."