INTRODUCTION. 35 



The sense in which the term Cause, also, is to be employed, should be clearly 

 understood at the outset of any scientific inquiry that involves its use; more 

 especially, since there is a considerable discrepancy between the popular accepta- 

 tion of the word, and the meaning which is now generally assigned to it by logi- 

 cians ; and it is peculiarly necessary for the correctness of Medical reasoning, 

 that its import should be definitely settled. When the " cause" of any event is 

 spoken of, in common parlance, we certainly attach to the term the idea of power, 

 at the same time that we include the notion of the conditions under which that 

 power operates; and this practical view of the case will be found (as the Author 

 believes) to be the correct one. On the other hand, the logician draws a dis- 

 tinction between the "efficient" and the "physical" cause of any phenomenon, 

 dismisses the former as a matter with which scientific inquiry is not legitimately 

 concerned, and applies himself to the consideration of the latter alone, which he 

 defines to be " the antecedent, or the concurrence of antecedents, on which it is 

 invariably and unconditionally consequent." (Mill, op. cit.) But when this 

 assemblage of antecedents is analyzed, it is uniformly found that they may be 

 resolved into two categories, which may be distinguished as the dynamical and 

 the material : the former supplying the force or power to which the change must 

 be attributed ; whilst the latter afford the conditions under which that power is 

 exerted. Thus in a Steam-Engine, we see the dynamical agency of Heat made 

 to produce mechanical power, by the mode in which it is applied first, to impart 

 a mutual repulsion to the particles of water, and then, by means of that mutual 

 repulsion, to give motion to the various solid parts of which the machine is coin- 

 posed. And thus, if asked what is the cause of the movement of the Steam- 

 Engine, we distinguish in our reply between the dynamical condition supplied 

 by the Heat, and the material condition (or assemblage of conditions) afforded 

 by the collocation of the boiler, cylinder, piston, valves, &e. So, again, if we are 

 asked what is the cause of the movement of a spinning-jenny, we refer it to its 

 connection by bands or wheels with some shaft, which itself derives its power to 

 move from a steam-engine or water-wheel ; these material collocations here again 

 serving to supply the conditions under which that Force becomes operative. In 

 like manner, if we inquire into the causes of the germination of a seed, which 

 has been brought to the surface of the earth, after remaining dormant, through 

 having been buried deep beneath the soil, for (it may be) thousands of years 

 we are told that the phenomenon depends upon warmth, moisture, and oxygen : 



the discovery of a scientific law affords a sufficient account of the occurrence of natural 

 phenomena ; and that the notion of the personal agency of the Deity in their production is, 

 therefore, an unwarrantable assumption. 



