INSTINCT. 



25 



" jind binding nature fast in fate, 



Left free the human will," 

 is inconsistent with a striking passage in the 

 Essay on Man : 

 " Who knows but He whose hand the lightning 



forms, 

 Who heaves old ocean, and who wings the 



storms, 



Pours fierce ambition in a Caesar's mind, 

 Or turns young Ammon loose to scourge man- 

 kind ? '* 



But if the foregoing statement of the mode 

 of action of the only voluntary power which we 

 are conscious of possessing over the train of our 

 thoughts is correct, it does not appear possible 

 to deny that ambition or any other passion may 

 be infused into any human mind, without de- 

 stroying the consciousness, or suspending the 

 action of that voluntary power. And if we 

 reflect on the characteristics of many nations 

 that have appeared on the earth's surface on 

 the taste and genius of the Greeks, the mili- 

 tary spirit of the Romans, the restless energy 

 of the northern nations, the maritime adven- 

 ture and commercial enterprise of Britain and 

 America and contrast these with the stationary 

 civilization of China, or the languid, if not re- 

 trograde condition of Italy, Spain, or Greece 

 is it unreasonable to suppose that the designs of 

 Providence as to the progress of the human 

 race are sometimes carried into effect by an oc- 

 casional infusion into many individuals of our 

 species, of feelings and desires, of the ultimate 

 object of which they have as little perception 

 as animals have of the purposes of their in- 

 stincts ? But to prosecute this speculation 

 farther would be foreign to the object of this 

 paper. 



It is still to be remarked, in regard to in- 

 stincts, that they have been long and justly 

 regarded as among the most important pheno- 

 mena in nature, in reference to the doctrine of 

 final causes, or the inferences of design, and of 

 the adaptation of means to ends in the arrange- 

 ment of the universe ; and it is important to 

 set in as clear a view as possible the proper use 

 to be made of them in that enquiry. 



In fact, the whole plan of the construction of 

 all the different classes of animals bears refe- 

 rence to the instincts with which they are en- 

 dowed, and would be useless without them. 

 If the fangs and claws of the lion, the jaws 

 and stomachs of the ox or the camel, or the bill 

 and gizzard of the turkey, are admirably 

 adapted for the prehension and subdivision of 

 their respective aliments, as well as their organs 

 of digestion for the assimilation of their food, 

 all these provisions would have been useless, 

 but for the instincts which nature has im- 

 planted in these animals, by which their proper 

 nourishment is sought, and the first part of the 

 process of its assimilation .is directed. 



The mutual adaptation of instincts to struc- 

 ture, of structure to instincts, and of both to 

 the ends of their creation throughout every 

 part and function of an animal, and throughout 

 every grade of the animal creation, has been 

 illustrated by many authors, but perhaps most 

 efficiently by Paley, as the most satisfactory of 

 all the indications of the adaptation of means 



to ends which the study of the universe pre- 

 sents. 



It is indeed so clearly the fact that all the 

 arrangements of the structure of an animal are 

 subordinate to the instincts with which it is 

 endowed, that the whole study of Comparative 

 Anatomy, and the whole classification of ani- 

 mals in so far as it is founded on their varieties 

 of structure, require to be regulated by this 

 consideration. The general principle by which 

 the details of these sciences are held together 

 may be stated to be this : that while nature 

 has observed a certain unity of plan in the con- 

 struction, certainly of all the vertebrated, per- 

 haps to a certain degree of all, animals, she has 

 likewise introduced in all parts of the scale 

 just such modifications of that plan as the si- 

 tuation in which each animal is placed, and the 

 office it has to perform, or as the French ex- 

 press it, as the conditions of its existence, 

 demand ; and then has implanted in it pre- 

 cisely such instincts as are required to enable it 

 to maintain itself to turn those provisions to 

 account to enjoy its allotted portion of sen- 

 sitive pleasure, and to fulfil the other objects of 

 its creation, under those conditions. 



The study of the instincts of animals may 

 be said, therefore, to hold a necessary interme- 

 diate place between the study of their struc- 

 ture, and that of the ends or objects of their 

 creation the structure being subordinate to 

 the instincts, as these are subordinate to the 

 objects of existence ; and it is by attending to 

 them that the immense extent and infinite va- 

 riety of the adaptation of means to ends in the 

 animal creation is perhaps most distinctly per- 

 ceived. 



It is stated by Mr. Whewell, that although 

 the study of Final Causes has been often re- 

 jected from the science of Physiology, yet 

 it has been found impossible to keep them se- 

 parate. " The assumption of final causes in 

 this branch of science is so far from being ste- 

 rile, that it has had a large share in every disco- 

 very which is included in the existing mass of 

 knowledge. The doctrine of the circulation of 

 the blood was clearly and professedly due to 

 the persuasion of a purpose in the circulatory 

 apparatus.''* But there appears to be some 

 ambiguity in this statement. The term 

 physiology is properly applied to the in- 

 vestigation of the physical causes of the 

 phenomena of life of the powers which 



are in operation, 



and the conditions under 

 which they operate, in producing these phe- 

 nomena. It is true that the different func- 

 tions of life are dependent on one another in 

 any individual animal ; and the science of phy- 

 siology is most conveniently taught by arrang- 

 ing their functions in the order of their de- 

 pendence, and assigning, therefore, the final 

 cause of each, after explaining the manner in 

 which it is carried on. It is true, also, that the 

 study of the uses to which the different func- 

 tions are subservient, i. e. the study of final 

 causes, has often led to the detection of phy- 

 sical causes in this as in other sciences. But 



* Hist, of the Inductive Sciences, vol. iii. p. 467. 



