INTRODUCTION. 



CHAPTER I. 



SUBJECTS OF HUMAN KNOWLEDGE. 



THE intelligent Reader, whose eye these pages may reach, has 

 doubtless already been led to reflect on the great variety and vast ex- 

 tent of human knowledge. In the country, he has probably observed 

 the wondrous works of nature, fresh from the hand of their Divine 

 Author; and in the city, he has viewed those works, modified, in a 

 thousand ways, by the less plastic labors of art. In society, he has 

 probably studied mankind in their diversified aspects ; and in solitude, 

 has endeavoured to know himself, and to trace his origin, and that 

 of all created things, back through the range of time, and upward 

 through the chain of secondary causes, to the first and sole Great 

 Cause of all. To such Readers, a review of these various subjects, 

 so classified as to show their mutual relations or dependencies, and 

 accompanied by some distinct views of their facts and principles, his- 

 tory and uses, cannot fail to be interesting, if not entertaining. 



We will commence by reconnoitring the field of knowledge, that 

 we may afterward survey it in a more methodical manner. Mind 

 and matter, active or passive, separate or combined, form the subjects 

 of all our ideas ; body and spirit being the only modes of exist- 

 ence with which we are acquainted. The mind is of course concern- 

 ed in the acquisition of all human knowledge ; so that the study of 

 matter is distinct from mind, only as regards the objects which are 

 studied. And as we cannot comprehend the nature or essence of 

 our own minds, neither can we understand the nature of matter, nor 

 the mode nor the origin of its existence ; but only its phenomena and 

 properties, so far as they are discoverable by the agency of our 

 senses. 



In examining the properties of matter, we have frequent occasion 

 to measure distances, bulks, or weights ; and to express the same by 

 numbers, with reference to some standard unit ; as five miles, ten 

 cubic feet, or fifteen pounds. To express and compare these numbers, 

 in various ways, was the object of Arithmetic: and to represent un- 

 known numbers by symbols, and afterwards discover their value from 

 their relations to certain known numbers, was the higher office of 

 Algebra. It was also found desirable sometimes to express quanti- 

 ties by extent or magnitude, having particular reference to figure or 

 shape : and hence the origin of Geometry. The application of num- 

 bers to measure various figures and curves, was a still higher step in 

 these auxiliary sciences ; and the mode of discovering the relations 



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