many types of deception described, but that they are too complicated and varied to be capable of rigid analysis: the moment deception becomes conscious, there must be acting and subterfuge to maintain the appearance of sincerity. If we add this great class of deceptions to those already enumerated, we may perhaps realize how vast is its domain, and what a long, what a sad chapter would be necessary to contain the history of human error.
Ethics is so closely related to psychology—right knowing to right doing—that a brief "hæc fabula docet" by way of summary may not be out of place. We find, first, a class of sense-deceptions which are due to the nature of sense-organs, and deceive only so long as their true nature remains unknown. These are neither pernicious nor difficult to correct. Next come a class of deceptions that deceive because we are ignorant of the possibilities of conjuring and pronounce upon the possibility or impossibility of a certain explanation in advance of complete knowledge; of this I have already said enough. But most dangerous and insidious are the deceptions in which self-deception plays the leading rôle. The only safeguard here is a preventive: the thorough infusion of sound habits of thought, a full recognition of the conditions under which the testimony of consciousness becomes doubtful, an appreciation of the true value of objective scientific evidence, and an inoculation against the evils of contagion by an independent, unprejudiced logical schooling. When once these evils of self-deception, fed by the fire of contagion and emotional excitement have spread, reason has little control. As Prof. Tyndall tells us, such "victims like to believe, and they do not like to be undeceived. Science is perfectly powerless in the presence of this frame of mind. . . . It [science] keeps down the weed of superstition, not by logic, but by slowly rendering the mental soil unfit for cultivation." With the spread of education, with the growth of the capacity to profit by the experiences of others, with the recognition of the technical requisites that alone qualify one for a judgment in such matters, with a knowledge of the possibilities of deception and of the psychological processes by which error is propagated, the soil upon which spiritualism and kindred delusions can flourish will be rendered unfit.