w the environment seems to mould the organism, from another
point the organism seems to be master of its environment. Going behind the
change of circumstances, we may raise the question, the old question, Was
life in its essence worth more then than now? Has there been a real
advance?

Let me at once relieve your minds by saying that I propose to leave this
question in the main unanswered. It may be, or it may not be, that man's
grasp of the beautiful and of the good, if not looser, is not firmer than
it was a hundred years ago. It may be, or it may not be, that man is no
nearer to absolute truth, to seeing things as they really are, than he was
then. I will merely ask you to consider with me for a few minutes how far
and in what ways man's laying hold of that aspect of, or part of, truth
which we call natural knowledge, or sometimes science, differed in 1799
from what it is to-day, and whether that change must not be accounted a
real advance, a real improvement in man.

I do not propose to weary you by what in my hands would be the rash effort
of attempting a survey of all the scientific results of the nineteenth
century. It will be enough if for a little while I dwell on some few of
the salient features distinguishing the way in which we nowadays look
upon, and during the coming week shall speak of, the works of nature
around us--though those works themselves, save for the slight shifting
involved in a secular change, remain exactly the same--from the way in
which they were looked upon and might have been spoken of at a gathering
of philosophers at Dover in 1799, and I ask your leave to do so.

In the philosophy of the ancients earth, fire, air, and water were called
"the elements." It was thought, and rightly thought, that a knowledge of
them and of their attributes was a necessary basis of a knowledge of the
ways of nature. Translated into modern language, a knowledge of these
"elements" of old means a knowledge of the composition of the atmosphere,
of water, and of all the other things which we call matter, as well as a
knowledge of the general properties of gases, liquids, and solids, and of
the nature and effects of combustion. Of all these things our knowledge
to-day is large and exact, and, though ever enlarging, in some respects
complete. When did that knowledge begin to become exact?

To-day the children in our schools know that the air which wraps round the
globe is not a single thing, but is made up of tw