can only mean that they had little conception of how much there is to
explain, and of what is meant by scientific explanation.

It is characteristic of this series of philosophers that their
attention was directed very largely upon the external world. It was
natural that this should be so. Both in the history of the race and in
that of the individual, we find that the attention is seized first by
material things, and that it is long before a clear conception of the
mind and of its knowledge is arrived at. Observation precedes
reflection. When we come to think definitely about the mind, we are
all apt to make use of notions which we have derived from our
experience of external things. The very words we use to denote mental
operations are in many instances taken from this outer realm. We
"direct" the attention; we speak of "apprehension," of "conception," of
"intuition." Our knowledge is "clear" or "obscure"; an oration is
"brilliant"; an emotion is "sweet" or "bitter." What wonder that, as
we read over the fragments that have come down to us from the
Pre-Socratic philosophers, we should be struck by the fact that they
sometimes leave out altogether and sometimes touch lightly upon a
number of those things that we regard to-day as peculiarly within the
province of the philosopher. They busied themselves with the world as
they saw it, and certain things had hardly as yet come definitely
within their horizon.

2. THE GREEK PHILOSOPHY AT ITS HEIGHT.--The next succeeding period sees
certain classes of questions emerge into prominence which had attracted
comparatively little attention from the men of an earlier day.
Democritus of Abdera, to whom reference has been made above, belongs
chronologically to this latter period, but his way of thinking makes us
class him with the earlier philosophers. It was characteristic of