76 MEMOIR OF DR. DALTON, AND . 



obtain, that it makes us readily believe that we may now 

 be living under the grossest delusions which a little spark 

 of genius might readily dispel, revealing to us a world entirely 

 different to that which we are accustomed to see ; and without 

 a doubt this is to a great extent the case. 



As an instance of the diflSculty of arriving at a rational con- 

 ception of material phenomena, but more especially in order 

 to give a sketch of the history of the subject, I shall adduce 

 the opinions shortly expressed of some of the most prominent 

 thinkers of ancient times. 



Much as has been written on this ancient part of philoso- 

 phical history, a full as well as distinct account is still wanting. 

 Most writers give us so much explanation, that we cannot 

 understand them : the collected fragments would form a 

 valuable volume. The physical has generally been given 

 as a mere appendage to the metaphysical history. 



Although the earliest opinions relate more directly to crea- 

 tion or cosmogony than to the nature of combinations, they 

 still are interesting in connection with our subject, as they 

 show us the early methods of viewing matter, and illustrate 

 the difficulties as well as progress of the subject. Of the 

 early Greek schools, where fragments only exist, I shall 

 give a few particulars taken chiefly from Ritter and Tiede- 

 mann, not giving the original words of the ancient authors, 

 some of which have been lost, and others greatly scattered.* 



Thales considered the earth to be a living being, and 

 the only primitive princij)le from which all things are 

 formed to be water. He observed, no doubt, that where 

 there is no water, there is no growth of vegetable or animal 

 life. The vegetables are fed by the rain ; they contain water 

 in their juices, or they do not live. Animals dried up are 

 dead. Life goes on in the world only with water, even the 



• Ritter's '• Geschichte der Philosophie." I used the French edition. 

 Tiedemann's " Geist der Spekulativen Philosophie." 



