24 WHY THEORISTS OFTEN MISTAKE. 



singular properties were satisfactorily ascertained and 

 established. 



This extraordinary menstruum, the most active with 

 which we are acquainted in nature, is now well known 

 by the name of gastric juice, so called from the Greek 

 term for the organ that pours it forth. 



Its apparent simplicity of composition is as remark- 

 able as its digestive power; for, in a pure and healthy 

 state, it is a thin, transparent, and uninflammable fluid, 

 of a weak saline taste, and utterly destitute of smell. 

 Its antiputrescent property is of as extraordinary a 

 nature as its digestive ; for it will render perfectly sweet 

 the most offensive and putrid food that gipsies or hungry 

 dogs can be made to swallow, in about half an hour after 

 such food has been exposed to its action. This gastric 

 juice farther possesses, in an equal degree, both these 

 curious powers of dissolution and restoration to 

 sweetness, as well out of the body as in the stomach 

 itself. 



I present this example, that you may trace the origin 

 of the mistakes into which theorists are often apt to 

 fall in their speculations upon the causes of things. 

 Measuring the operations of nature by their own imper- 

 fect powers, they take it for granted that that which 

 appears to be elaborate, must, in fact, be so. Hence, in 

 tracing her, they overlook the principle of simplicity 

 which is stamped upon her footsteps ; surround them- 

 selves with a complex machinery; and lose their aim 

 and their path by the mere multiplicity of their agencies ; 

 till accident, in a lucky hour, points out the right, the 

 long-sought track. 



We have seen, in the principal cases which I have 

 selected, how much has sprung from apparent accident. 



