INTRODUCTION. 
WE often hear the word Nature used in such a way that it is 
difficult to know what meaning is attached to it. Some denote 
thereby the system of all the forces to which matter is subjected, 
and thus distinguish between Nature and the Universe; under- 
standing by the last the entire complex of created bodies. 
But such a distinction is quite arbitrary. The word Nature, 
introduced into modern languages from the Latin, is derived from 
nasct, to be born, to come into being’. In this sense we call the 
ageregate of all that comes, or has come, into being, and is for us 
an object of observation either by external sense or internal percep- 
tion, Nature—the material world and the spiritual world—Nature 
in space and Nature in thought. Finally we oppose Nature to Art, 
understanding by the last whatever change the intellect of man has 
induced upon the products of Creation, in order to satisfy his wants, 
or to enhance his enjoyments. 
However different these and other meanings may be, we may 
admit that to be the most general which defines nature as the 
material world, the world of matter, all that is created or has being, 
together with the forces inherent in the matter, and the laws 
according to which they act. The knowledge of this whole, so 
stupendously vast, the ancients named physica: and considered to 
be a part of the philosophy which they termed a science of divine 
and human things and of their causes. But though this science, like 
nature its object, be one, yet its great extent on the one hand and 
the narrowness of the human intellect on the other, has rendered 
the subdivision of it necessary. Yet the limits of the different 
natural sciences can scarcely, on account of their mutual relations, 
1 So the Greek gious from piw. 
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