VALUES AND FINAL CAUSES 83 



widening range of application, affords the requisite means 

 of connexion. As soon as any fact has been reduced to 

 a place in a chain of sequences, we feel that the explanation 

 of its existence is sufficient. But even here, though we 

 need not inquire what the purpose is of the object we are 

 dealing with, our thought itself cannot act without a purpose. 

 That purpose is always one and the same, that is, the unifi 

 cation of knowledge, or, in other words, the satisfaction 

 of the impulse itself. Scientific thought cannot proceed 

 without classification, and the purpose of all classification 

 is to reduce single facts to series of facts. Here, however, 

 no further end need be assumed. A scientific explanation, 

 in cases where it can be obtained, is completely satisfactory ; 

 we need go no further. 



It is possible that this assertion, that the concept of pur 

 pose is not required when a scientific explanation is available, 

 may be disputed. We certainly should have no difficulty 

 in finding assertions to the contrary, and it is strictly relevant 

 to our present inquiry to consider what they amount to. 

 For this purpose I would venture to refer to a passage in 

 Dugald Stewart s Active and Moral Powers of Man (Book 

 III. iv). In that, he quotes Priestley s remark that while 

 we keep in view the great FINAL cause of all the parts 

 and the laws of nature, we have a clue by which to trace 

 the efficient cause : together with the report of a conversa 

 tion with Dr. Harvey, in which that great man is said to have 

 attributed his discovery of the circulation of the blood to 

 his observation that the valves of the veins were placed 

 in the body with no apparent design; and his conclusion 

 that they were meant to direct the flow of the blood to the 

 heart instead of to the limbs. 



Dr. Harvey s remark involves two entirely distinct proposi 

 tions. The first of these is that the determination of the 

 venous blood to the heart is the invariable result of the 

 valves in the veins a discovery which brings these organs 

 under the general law of uniform sequence ; the second is 

 that the venal circulation is a special instance of the general 

 law that all the processes of our organism are intelligently 



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