IMAGINATION. 153 



terrier which pines for its absent mistress an elaborate | 

 structure of abstract ideation, and the terrier's imaginative ' 

 faculty would begin to rival that of man. Of course it will 

 be said that abstraction presupposes imagination, and so 

 undoubtedly it does; still the two are not identical, as is 

 jDroved by the fact that for the building up of abstraction to 

 any exalted height, language, or mental symbolism of some 

 kind, is indispensable ; and mental symbols are so many 

 artifices for the saving of imagination. 



Now if at first sight it seems aljsurd to accredit a moUusk 

 with imaginatiun, we must remember exactly what we mean 

 by imagination in the lowest possible phase of its develop- 

 ment. We mean merely the power of forming a definite 

 mental picture, or of retaining a memory, no matter of how 

 rudimentary a kind ; provided that the memory implies some 

 dim idea of an absent object or experience, and not, as in the 

 case of an infant disliking the taste of strange milk, merely 

 an immediate perception of contrast between an habitual and 

 a present sensation. And that we find such a level of 

 mental development as low down in the zoological scale as 

 the Gasteropoda, would seem to be proved by the fact already 

 alluded to of limpets returning to their homes in the rocks 

 after feeding. Of course the mental image wdiich a limpet 

 forms of its home in a rock cannot be supposed to be com- 

 parable in point of vividness or complexity with the mental 

 image that a horse retains of its stall, or a dog of its kennel ; 

 still, such as it is, it is a mental imao-e, and therefore betokens 

 imagination. More vivid, and therefore more definite, is the 

 mental image that a spider forms of her lair, who when dis- 

 lodged and carried away to a short distance again returns to 

 her old home. (Level 20.) AVith a stiU further advance in 

 the power of mental imagery (level 21) we find supplied the 

 psychological conditions for the ideation of cold-blooded Ver- 

 tebrata, such as the determination displayed by migratory 

 Fishes (notably the salmon) to visit particular localities in 

 the spawning season. On the next level (22) we reach the ^ 

 higher Crustacea, which, as we have already seen, are able to \\ 

 imagine in a high degree. Next we come to Keptiles, con- ■ • 

 cerning which I may quote the following anecdote from 

 Lord Monboddo : " I am well informed of a tame serpent in 

 the East Indies, which belonged to the late Dr. Vigot, once 

 kept by him in the suburbs of Madras. This serpent was 



