I. The nature of perception; its subjective and objective factors 275
II. Illustrations of the effects of the subjective factor 279
III. Perception as modified by attention and by the mental concept; illustrations; equivocal drawings 282
I. The nature of prepossession; pedagogical illustrations 296
II. Illustration derived from the experience of the Census Bureau 301
II. Muscle-reading; method of recording involuntary movements 308
III. Illustrations and description of records of involuntary movements 312
IV. Interpretation and analysis of records of involuntary movements 321
V. Influence of the nature of the object of attention upon involuntary movements 330
VI. Other forms of involuntary indications; "involuntary whispering;" the subconscious 334
II. The retention of vision in dreams as dependent upon the age of the loss of sight; the "critical period;" the investigation of Heermann in 1838; the status as to "dream-vision" of the partially blind 340
III. Corroborations of the above results by other evidence; the dreams of the blind-deaf; dreams of Laura Bridgman; Helen Keller's account of her dream-life; interpretations 345
IV. Distinctions in dream-life of incidents experienced during the period of sight from those of the blindness period; the imagination of the blind; illustrations of their dreams 360
If that imaginary individual so convenient for literary illustration, a visitor from Mars, were to alight upon our planet at its present stage of development, and if his intellectual interests induced him to survey the range of terrestrial views of the nature of what is "in heaven above, or on the earth beneath, or in the waters under the earth," to appraise mundane opinion in regard to the perennial problems of mind and matter, of government and society, of life and death, our Martian observer might conceivably report that a limited portion of mankind were guided by beliefs representing the accumulated toil and studious devotion of generations,--the outcome of a slow and tortuous but progressive growth through error and superstition, and at the cost of persecution and bloodshed; that they maintained institutions of learning where the fruits of such thought could be imparted and the seeds cultivated to bear still more richly; but that outside of this respectable yet influential minority, there were endless upholders of utterly unlike notions and of widely diverging beliefs, clamoring like the builders of the tower of Babel in diverse tongues.