rder and accuracy increase steadily as science advances. It is thus a
type of progress, for it is a constant growth in the fullness, accuracy
and simplification of our experience. From the dawn of science,
therefore, man must have acquired standards and instruments of
measurement and means of handing on his observations to others. Thus
writing must have been invented. But in the second place, there is
always involved in this orderly description, so far as it is scientific,
the element of prediction. The particular description is not scientific.
'I saw a bird fly' is not a scientific description, however accurate;
but 'The bird flies by stretching out its wings' is. It contains that
causal connexion or element of generality which enables us to predict.

Before entering on a historical sketch of the most perfect example of
human progress, it is of the first importance to realize its social
foundation. This is the key-note, and it connects science throughout with
the other aspects of our subject. Knowledge depends upon the free
intercourse of mind with mind, and man advances with the increase and
better direction of his knowledge. But when we consider the implications
of any generalization which we can call 'a law of nature' the social
co-operation involved becomes still more apparent. Geometry and
astronomy--the measurement of the earth and the measurement of the
heavens--dispute the honour of the first place in the historical order.
Both, of course, involved the still more fundamental conception of number
and the acceptance of some unit for measurement. Now in each case and at
every step a long previous elaboration is implied of intellectual
conventions and agreements--conscious and unconscious--between many minds
stretching back to the beginnings of conscious life: the simplest element
of thought involves the co-operation of individual minds in a common
product. Language is such a common product of social life and it prepares
the ground for science. But science, as the exact formulation of general
truths, attains a higher degree of social value, because it rises above
the idioms of person or race and is universally acceptable in form and
essence. Such is the intrinsic nature of the process, and the historical
circumstances of its beginnings make it clear. It was the quick mind of
the Greek which acted as the spark to fire the trains of thought and
observation which had been accumulating for ages through the agency of the