Inquiry into the Nature and Properties of the Blood. 203 



universe is presented to the eyes as a single indistinct thing, 

 a shapeless chaos : yet all things in process of time become 

 more distinct, and at length make their way to the rational 

 faculty of the mind ; — thus are we a long time in becoming ra- 

 tional. 



Whether we have discovered the truth or not, respecting 

 any subject, is easily ascertained ; for all experience will then 

 spontaneously bear testimony in its favour, so likewise will 

 every rule of true philosophy : for when truth is at hand, no- 

 thing whatever refuses it its suffrage ; hence it immediately 

 manifests itself, and commands belief, or, as is commonly ex- 

 pressed, presents itself naked. 



Nothing can introduce us to the causes of things, or to 

 truth, but expeiience alone : for when the mind or contem- 

 plative faculty is left to expatiate without restraint, or without 

 experience for its guide, how easily does it fall into error, and 

 go stumblinjT on from one absurdity to another; and if it then 

 looks to experience for confirmation and patronage, the at- 

 tempt will be wholly useless and vain. To consult experience 

 after assuming our principles is an erroneous mode of pro- 

 ceeding : we should on the contrary consult expei'ience first, 

 and deduce our principles from it ; when we are led away by 

 reasoning alone, we are not unlike those who, with their eyes 

 blindfolded, as is sometimes practised in childish sport, be- 

 lieve themselves to be walking in a straight direction, but who 

 on the removal of the bandage find that they have wandered 

 greatly from the path, and that if they had continued their 

 blind progress they would have arrived by a circular course, 

 at a place the very opposite to that of their destination. 



But it may be inquired whether we have at the present day 

 a sufficient store of experience or of facts to enable us to dis- 

 cover Nature's secrets so successfully as the above considera- 

 tions would lead us to expect, without its being necessary to 

 suffer our minds to wander into the wild field of conjecture 

 uurestrained by experience. It cannot be denied that our ex- 

 perience or our knowledge of any one individual thing, let it 

 even be enriched and increased by the accumulated experience 

 of ages, can never sufHce to complete the investigation of the 

 subject to which it relates, to its very and inmost causes. But 

 if all that is known, or all our general experience in anatomy, 

 medicine, chemistry, physics, and the other natural sciences, 

 be called to our aid in die exploi'ation and investigation of any 

 i idividual thing, — as in this instance in the investigation of the 

 blood, we may allirni that we are at this day sufficiently pro- 

 vided for the purpose. 



When we confine our experimental research to a single ob- 

 2 D 2 ject, 



