PREFACE. 



IN submitting the accompanying Treatise to the public, it may be 

 proper to precede it by a few facts 'and remarks relative to its origin, 

 plan, and purpose. In the summer of 1849, on retiring from the edi- 

 torial charge of a Philosophical Journal, the writer announced his 

 intention to prepare and publish, as soon as convenient, a work on 

 Psychology a subject then, as now, exciting much interest among a 

 class of readers with whom he had been holding weekly communion. 

 A manuscript of such a work was, during the few ensuing months, 

 nearly finished ; but various circumstances and considerations arose to 

 prevent its publication, among the chief of which were, first, that with 

 the materials of psychological science then unfolded, I found it impos- 

 sible to bring the work to a desired state of perfection ; and, secondly, 

 that facts and principles such I was then able, only, to set forth, were 

 already rapidly forcing themselves into general notice in another way. 

 I concluded, therefore, to await the unfolding of further light upon a 

 subject of which, at that time, no one could claim more than a very 

 superficial knowledge, and to postpone the publication of the results 

 of my investigations until they were further matured, and until the 

 state of the public mind, upon questions to which they related, gave a 

 fair indication that some particular use, not accomplished by other de- 

 velopments, might be possibly subserved in submitting them to general 

 perusal. These statements involve an explanation and apology to a 

 large portion of my former readers, who, as I learn, felt disappointed 

 at the non-appearance of the announced publication at the time it was 

 expected, and whose letters of inquiry respecting it I have, in some 

 instances, been reluctantly compelled to leave unanswered. 



As investigations have been continued upon the great subject of 

 Psychology, together with its cognate and still higher themes, it has, 

 of course, greatly expanded ; until, in the aspect which the ques- 

 tion finally assumed, it was perceived to be impossible to give any ade- 

 quate exposition of the great realm of being within man, without the 



