ORDER PACHYDERMATA. 365 



But in the human mind, and probably also in the brute, 

 a certain development of intellectual power speedily takes 

 place ; and it soon becomes difficult to trace the actions of 

 the growing subject to their source, whether to the voluntary 

 result of reason, or the involuntary impetus of instinct. As 

 the former proceeds, however, especially in man, the diffi- 

 culty vanishes, and we are soon enabled to observe that 

 the simple necessities of life are seized and applied by the 

 action of reason ; and as this state of things advances, in- 

 stinct probably recedes. There are, however, symptoms of 

 its action even in the adult. There is strong reason to be- 

 lieve that the impulse to propagation, and to parental affec- 

 tion, is not altogether independent of passion or instinct. 

 The fear of death also, or rather of nonentity, seems so 

 intimately connected with our nature as to be instinctive ; a 

 natural feeling, which it is the business of reason to subdue 

 within legitimate bounds. 



But to illustrate the definition of pure unmixed instinct, 

 let us instance two or three examples ; the more common 

 and notorious the better. 



It is a curious mathematical problem at what precise 

 angle the three planes which comppse the bottom of a cell 

 ought to meet, in order to make the greatest possible saving 

 of material and labour. This is one of those problems be- 

 longing to the higher part of mathematics, which are called 

 problems of maxima and minima. Maclaurin resolved it 

 by a fluxionary calculation, which is to be found in the 

 Transactions of the Royal Society, and determined pre- 

 cisely the angle required. Upon the most exact mensura- 

 tion the subject could admit, he afterwards found that it 

 is the very angle in which the three planes in the bottom 

 of the cell of a honey-comb actually meet. " Shall we ask,' 1 

 says Dr. Reid, " who taught the bees the property of solids, 

 and to resolve problems of maxima and minima 1 It need not 

 be replied, that they are as ignorant of these properties as 



Vol. III. 2 C 



