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Introductory. 
PHysics or Puysican Scimnce, from the Greek word physis, nature, 
was the name originally applied to the whole of man’s knowledge 
regarding Nature or the material universe. The universe is composed of 
an immense variety of materials or objects, many of which bear a general 
resemblance to each other. This resemblance has led to a classification 
of these materials into three Kingdoms—the Animat, the VEGETABLE, 
and the Minrraz; and the minute description of these classes consti- 
‘tutes the science of Naturat History. Besides this resemblance 
between particular objects, it has been found that certain motions: or 
changes, called phenomena [Gr., ‘appearances’], are continually going on 
among the objects themselves. And as, for convenience, the materials of 
the universe have been arranged under separate classes, there is likewise 
a classification of the phenomena to which they are subject. There is 
one class of phenomena which are always accompanied by a very 
decided change in the bodies themselves: the science which treats of 
these phenomena is called CHEmistRY. A second class, caused by the 
action of Lzfe, is included under the science of Paystiotocy. A third 
class is formed of those phenomena which are caused by the action of 
Mind: these belong to the science of Mrentan PuritosopHy. The 
fourth and last class of phenomena includes those which are neither 
accompanied by any essential change in the object, nor caused by the 
action of life or of mind, but which are due simply to the properties of 
bodies as bodies, and are common to all objects, animate or inanimate. 
It is to the knowledge of this last class of phenomena that the name of 
Puysics, PHysican Science, or NaturAL PHILosopHy is now properly 
applied. 
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