88 MEMOIR OF DR. DALTON, AND 



out their general principle to the utmost, and, of course, 

 leads to an entire want of definition of natural things. 

 Knowledge is gained by observing qualities, not by con- 

 founding them ; by seeing distinctions, not by hiding them. 

 The most contradictory assertions of all kinds have been 

 made on the subject, especially after the great masters had 

 done their utmost services. We must not suppose the above 

 to be merely ridiculous. It evidently involves an extension 

 of the idea of body, the limits of which are still unknown, 

 and in some form or other it has often risen, and is likely 

 again to rise, for discussion. 



We find that ir. nearly all the cases alluded to matter has 

 been able to put on various forms, and that it is of itself 

 a mere abstraction. There is, in nearly all, a substratum 

 more or less decidedly expressed. That is, a matter without 

 properties to the senses, but capable of putting on all. The 

 mater^ mother of all substances. With this idea before us, 

 most of the opinions will have some connection and ration- 

 ality. Among those who denied the existence of the reality 

 in the things perceived by the senses, we can find very little 

 directly relating to the subject; but we must ever view with 

 admiration and gratitude the acute minds which have done so 

 much of the preliminary work necessary both for physics and 

 philosophy. 



The atomic system of the ancients was most fully ex- 

 plained by Lucretius, and leaving the nice distinctions of the 

 stoics, and their semi-metaphysical modes of looking on 

 matter, let us look more fully at this system than the others, 

 as it may be said to form the beginning of the atomic theory, 

 although the short and meagre introduction preceding may 

 not be without interest to such as have not had time to read 

 of the struggles of the mind in early times towards a rational 

 oxpression of phenomena. It was a struggle of the most 

 gifted minds in some of the most brilliant days of the world. 



