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 

 proved 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 sisrht it seems absurd to accredit a mollusk 

 with imagination, 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 alieady 

 alluded to of limpets returning to their homes in the rocks 

 after feeding. Of course the mental image which a limpet 

 forma 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 image, 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 

 hei old home. (Level 20.) With a still 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 Crustai ea, which, as we have already seen, are able to 

 imagine in a high degree. Next we come to Reptiles, con- 

 cerning which 1 may quote the following anecdote from 

 I.oid Monboddo: " I am well informed of a tame Berpent in 

 the East Indies, which belonged to the late I>r. Vigot,once 

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



