The object of this work is to provide an introduction to the study of "thought" as it has developed itself within the confines of the Practical Psychology. Interest in Concentration, Mind, Mental Discipline, the intelligent treatment and moral management of Mental Maladies, has in recent times become so pronounced and widespread that it is hoped that, even amongst the various and excellent works which have appeared in response to that interest, room may perhaps be found for an attempt to present the subject in its logical sequence, and in such a form as may best meet the wants of the interested student.