t against this must be placed
as something analogous in animals, the fact that they learn cunning
and caution through long continued persecution. Even the use of tools
is not in itself peculiar to man (monkeys use sticks, stones and
twigs), but man alone fashions and uses implements _designed for a
special purpose_. In this connection the remarks taken from Lubbock in
regard to the origin and gradual development of the earliest flint
implements will be read with interest; these are similar to the
observations on modern eoliths, and their bearing on the development
of the stone industry. It is interesting to learn from a letter to
Hooker,[96] that Darwin himself at first doubted whether the stone
implements discovered by Boucher de Perthes were really of the nature
of tools. With the relentless candour as to himself which
characterised him, he writes four years later in a letter to Lyell in
regard to this view of Boucher de Perthes' discoveries: "I know
something about his errors, and looked at his book many years ago, and
am ashamed to think that I concluded the whole was rubbish! Yet he has
done for man something like what Agassiz did for glaciers."[97]

To return to Darwin's further comparisons between the higher mental powers
of man and animals; He takes much of the force from the argument that man
alone is capable of abstraction and self-consciousness by his own
observations on dogs. One of the main differences between man and animals,
speech, receives detailed treatment. He points out that various animals
(birds, monkeys, dogs) have a large number of different sounds for
different emotions, that, further, man produces in common with animals a
whole series of inarticulate cries combined with gestures, and that dogs
learn to understand whole sentences of human speech. In regard to human
language, Darwin expresses a view contrary to that held by Max Mueller:[98]
"I cannot doubt that language owes its origin to the imitation and
modification of various natural sounds, the voices of other animals, and
man's own instinctive cries, aided by signs and gestures." The development
of actual language presupposes a higher degree of intelligence than is
found in any kind of ape. Darwin remarks on this point:[99] "The fact of
the higher apes not using their vocal organs for speech no doubt depends on
their intelligence not having been sufficiently advanced."

The sense of beauty, too, has been alleged to be peculiar to man. In
r