lphabet of Nature. But the
playing period is much more; it is one of the few opportunities animals
have of making experiments without too serious responsibilities. Play is
Nature's device for allowing elbow-room for new departures
(behaviour-variations) which may form part of the raw materials of
progress. Play, we repeat, gives us a glimpse of the possibilities of
the mammal mind.

Other Glimpses of Intelligence

A squirrel is just as clever as it needs to be and no more; and of some
vanishing mammals, like the beaver, not even this can be said. Humdrum
non-plastic efficiency is apt to mean stagnation. Now we have just seen
that in the play of young mammals there is an indication of unexhausted
possibilities, and we get the same impression when we think of three
other facts. (_a_) In those mammals, like dog and horse, which have
entered into active cooperative relations with man, we see that the mind
of the mammal is capable of much more than the average would lead us to
think. When man's sheltering is too complete and the domesticated
creature is passive in his grip, the intelligence deteriorates. (_b_)
When we study mammals, like the otter, which live a versatile life in a
very complex and difficult environment, we get an inspiriting picture of
the play of wits. (_c_) Thirdly, when we pass to monkeys, where the
fore-limb has become a free hand, where the brain shows a relatively
great improvement, where "words" are much used, we cannot fail to
recognise the emergence of something new--a restless inquisitiveness, a
desire to investigate the world, an unsatisfied tendency to experiment.
We are approaching the Dawn of Reason.

THE MIND OF MONKEYS

Sec. 8

There is a long gamut between the bushy-tailed, almost squirrel-like
marmosets and the big-brained chimpanzee. There is great variety of
attainment at different levels in the Simian tribe.

Keen Senses

To begin at the beginning, it is certain that monkeys have a first-class
sensory equipment, especially as regards sight, hearing, and touch. The
axes of the two eyes are directed forwards as in man, and a large
section of the field of vision is common to both eyes. In other words,
monkeys have a more complete stereoscopic vision than the rest of the
mammals enjoy. They look more and smell less. They can distinguish
different colours, apart from different degrees of brightness in the
coloured objects. They are quick to discriminate differences in the
shap