16 ON INSTINCT. 



Under thes, circumstances I shall beg your candid attention to a new view 

 of the subject, and a view that may tend to give us a more definite idea of the 

 nature of the action, and consequently of the extent and real meaning of the 

 term. 



In an early lecture of the preceding series* I endeavoured to point out the 

 common or essential, and many of the peculiar, properties of inorganic mat- 

 ter; and in a subsequent studyf I attempted to lay down the more prominent 

 characters by which inorganic is distinguished from organic matter, as a stone, 

 for example, from a plant or an animal. I observed that, on investigating the 

 history of the stone, it would be found to have been produced fortuitously ; 

 to have grown by external accretion, and only to be destructible by chemical 

 or mechanical means : while, on investigating the history of the plant or the 

 animal, it would be found to have been produced by generation ; to have 

 grown by nutrition, or internal instead of external accretion; and to be 

 destructible by death ; to be actuated by an internal power, and possessed of 

 parts mutually dependent, and contributing to each other's functions. I ob- 

 served farther, that in what this internal power consists we know not ; that in 

 plants and animals it appears to be somewhat differently modified, but that 

 wherever we meet with it we term it the PRINCIPLE OF LIFE, and character! e 

 the individual substance it actuates by the name of an organized being, from 

 its possession of organized parts, in contradistinction to all those substances 

 which are destitute as well of life as of internal organs, and which are hence 

 denominated unorganized. 



Upon another occasion I took a brief survey of the chief theories which 

 have been offered upon the nature of this mysterious and fugitive essence :| 

 which I observed was altogether a distinct principle from that of thought, 

 and from that of sensation, for both these must also be kept distinguished 

 from each other. I remarked, that in modern times it had at one period been 

 said to be derived from caloric, thermogen, or the elementary matter of heat, 

 as it exists in the organized system, from the well ascertained importance 

 of this substance (if it be a substance) towards the perfection, and even con- 

 tinuance, of all the vital functions : that at another time it was, for the same 

 reason, supposed to consist of oxygen introduced into the system by every 

 act of inspiration ; and still more lately of the Voltaic aura, in consequence 

 of those wonderful effects which this aura is now well known to produce on 

 the muscular fibres of animals, not only during life, but often for some hours 

 after death has taken place. I remarked farther, that Mr. John Hunter had 

 traced this living principle to many of the organized fluids, as well as to the 

 solids; and that he had especially developed it in the blood, which, coinci- 

 dently with the Mosaic declaration, he believed to be its immediate seat. 

 " The difficulty," observes he, " of conceiving that the blood is endowed with 

 life while circulating, arises merely from its being a fluid; and the mind not 

 being accustomed to the idea of a living fluid. "$ And I observed, that by a 

 variety of important and well-defined experiments, this enterprising and inde- 

 fatigable indagator had succeeded in proving, not only that it contributes in a 

 greater degree to the vital action and to the vital material of the general sys- 

 tem than any other constituent part of it, whether solid or fluid, but has all 

 the essential properties of life ; that it is capable of being acted upon, and 

 contracting, like the muscular fibre, upon the application of an appropriate sti- 

 mulus, as atmospheric air, for example ; on which occasion it becomes con- 

 stringed into that cake or coagulum which every one must have beheld in 

 blood drawn from the arm : that in all degrees of atmospherical temperature, 

 of heat or cold, which the body is capable of enduring, it maintains an 



and worms, is raised to a loftier and diviner rank than the peculiar principle by which man has hitherto been 

 supposed to exercise a dominion over the rest of creation. " In the lowest order of animals," says Dr. Han- 

 cock, " the divine energy seems to act with most unimpeded power. It is less and less concentrated in the 

 successive links of the living chain upward to man. The lowest animal has this divine power, not of free 

 choice, nor consciously : the HI.IKST of men has it also, but consciously and willingly: and it then be- 

 comes his ruling principle ; his divine counsellor ; his never-failing help ; a light to his feet, arid a lantern 

 to his path." Essay on Instinct, and its Physical and Moral Relations, p. 170513 



Series i. Lecture iv. f Series i. Lecture viii. 



. Series i. Lecture x. 3, Essay on the Blood, &c. p. 20. 



