WHAT MAY ANIMALS BE TAUGHT? 173 



got three. My experiments were not brought to a conclusion, but, if 

 they had been, it would not have been right to assume too readily that 

 the birds knew how to count. We should have to inquire whether I 

 had not involuntarily made some sign manifesting my intention. The 

 remarkable experiments of Mr. Cumberland have revealed to us a 

 whole category of motions of this kind which had never been taken 

 account of before. Who, previous to him, would have suspected that 

 the hand trembles in a different way when we think of seven and 

 when we think of three ? 



The solution is not advanced, then, when we tell of the cases, curi- 

 ous and interesting as they may be, in which animals seem to behave 

 like man ; or, to speak more exactly, these cases are proof only with 

 respect to persons who are inclined to attribute instincts alone to the 

 animal, and deny it reflection and calculation. As the philosophers 

 are still at this point, it may be well to try to undeceive them. Muta- 

 tis mutandis, the spider chooses the place for its web, and the bird for 

 its nest, as the colonist selects the location of his farm-house, or of the 

 pen for his goat or pig. I will agree that we may regard the laying 

 of the eggs, the making and shaping of the nest, and the selection of 

 materials as instinctive acts ; but the selection of the place is neces- 

 sarily of a deliberate and intelligent character. 



If there is a difference between animal and human intelligence, it 

 depends upon special causes, and these are what we are trying to dis- 

 entangle. I have already remarked that man has the faculty of think- 

 ing by symbols, while the animal appears not to have it. What is a 

 symbol ? It is not easy to define the term. Let us say provisionally 

 that it is a conventional mental sign, representing a clear abstraction. 

 The definition is neither very good nor very clear, but it will do, for 

 want of a better one. Before Thales and Pythagoras, thinkers had 

 distinguished between the common idea and the concept. The com- 

 mon idea is formed within us, we may say, almost physiologically. 

 Take, for example, the idea of horse. When I have seen twenty 

 horses, I have seen for twenty times the qualities which they all have 

 in common, while I have seen for a less number of times, or only once, 

 their respective individual qualities ; so that the common image en- 

 graves itself in the brain or in the sensorium, if that term is preferred, 

 in deeper and deeper lines and stands out strongly at the base of the 

 particular and fugitive images. 



The concept partakes of the common idea, and it might perhaps be 

 maintained that it is formed within us in the same manner. But the 

 degree of abstraction which it necessitates is infinitely more consider- 

 able. Let it be, for example, the number four. We agree, it is true, 

 that the idea of, say, any group of four fingers of the hand is a kind 

 of common idea ; but it is a good way from this idea, from this kind 

 of group, to that of four distant and different objects, like the four 

 limbs, the four largest cities in the world, the first four Roman em- 



