IIT ON ANIMAL LIFE 79 
moderates heat, the coin that purchases all 
things, the balance and weight that equals the 
shepherd with the king, and the simple with 
the wise.’ Some animals dream as we do; 
Dogs, for instance, evidently dream of | the 
chase. With the lower animals which cannot 
shut their eyes it is, however, more difficult 
to make sure whether they are awake or 
asleep. I have often noticed insects at night, 
even when it was warm and light, behave 
just as if they were asleep, and take no notice 
of objects which would certainly have startled 
them in the day. The same thing has also 
been observed in the case of fish. 
But why should we sleep? What a remark- 
able thing it is that one-third of our life should 
be passed in unconsciousness. “Half of our 
days,” says Sir T. Browne, “we pass in the 
shadow of the earth, and the brother of death 
extracteth a third part of our lives.” The 
obvious suggestion is that we require rest. 
But this does not fully meet the case. In 
sleep the mind is still awake, and lives a life 
of its own: our thoughts wander, uncon- 
trolled, by the will. The mind, therefore, 1s 
