548° RELATION OF INTELLIGENCE TO CEREBRUM. 
would behave as he did, that they never thought of tying 
him.” It were much to be wished, that all human beings’ 
would imitate this docile Elephant’s self-control. It is some-: 
times manifested, however, even in Infancy; the painful 
operation of lancing the gums being often sustained without 
a cry, from the consciousness of the benefit derived from it. 
718. It has been stated that the relative amount of Intelli- 
gence in different animals bears a pretty constant proportion 
to the size and development of the Cerebral hemispheres 
(§ 452). That size alone, however, does not produce the dif- 
ference, is eyident from a number of facts. As we advance 
from the lower to the higher Vertebrata, we observe an obvious 
advance in the complexity of the structure of the brain. In 
proportion to the increase in the number and depth of the 
convolutions by which its surface is extended (§ 456), do we 
find an increase in the thickness of the layer of grey or 
vesicular matter (§ 61), which seems to be the real centre of 
all the operations of the organ. The arrangement of the 
white or tubular tissue (§ 60), which forms the interior of 
the mass, also increases in complexity; and as we ascend 
from the lower Mammalia up to Man, we trace a great in- 
crease in the number of the fibres which establish communi- 
cations between different parts of the surface. Still there can 
be no doubt that the size of the Cerebrum, compared with that 
of the Spinal Cord and of the Sensory Ganglia at its summit, 
usually affords a tolerably correct measure of the intelligence 
of the animal ; and that, even in comparing together different 
Men, we shall find the same rule to hold good, when due 
allowance has been made for the comparative activity of their 
general functions, such as is expressed by the word tempera- 
ment. Thus, two men, having brains of the same size and 
general conformation, may differ greatly in mental vigour, 
because the general system of one performs its functions 
much more actively and energetically than that of the other. 
For the same reason, a man of small brain, but whose general 
habit is active, may have a more powerful mind than another 
whose brain is much larger, yet whose system is inert, his 
perceptions dull, and his movements languid. But of two 
men alike in these respects, and having the same general con- 
figuration of head, it cannot be doubted that the one with the 
larger brain will surpass the other. It is a striking fact, that 
