knowledge. Thus causal nature is a metaphysical chimera;
though there is need of a metaphysics whose scope transcends the
limitation to nature. The object of such a metaphysical science is not
to explain knowledge, but exhibit in its utmost completeness our concept
of reality.

However, we must admit that the causality theory of nature has its
strong suit. The reason why the bifurcation of nature is always creeping
back into scientific philosophy is the extreme difficulty of exhibiting
the perceived redness and warmth of the fire in one system of relations
with the agitated molecules of carbon and oxygen, with the radiant
energy from them, and with the various functionings of the material
body. Unless we produce the all-embracing relations, we are faced with a
bifurcated nature; namely, warmth and redness on one side, and
molecules, electrons and ether on the other side. Then the two factors
are explained as being respectively the cause and the mind's reaction to
the cause.

Time and space would appear to provide these all-embracing relations
which the advocates of the philosophy of the unity of nature require.
The perceived redness of the fire and the warmth are definitely related
in time and in space to the molecules of the fire and the molecules of
the body.

It is hardly more than a pardonable exaggeration to say that the
determination of the meaning of nature reduces itself principally to the
discussion of the character of time and the character of space. In
succeeding lectures I shall explain my own view of time and space. I
shall endeavour to show that they are abstractions from more concrete
elements of nature, namely, from events. The discussion of the details
of the process of abstraction will exhibit time and space as
interconnected, and will finally lead us to the sort of connexions
between their measurements which occur in the modern theory of
electromagnetic relativity. But this is anticipating our subsequent line
of development. At present I wish to consider how the ordinary views of
time and space help, or fail to help, in unifying our conception of
nature.

First, consider the absolute theories of time and space. We are to
consider each, namely both time and space, to be a separate and
independent system of entities, each system known to us in itself and
for itself concurrently with our knowledge of the events of nature. Time
is the ordered succession of durationless instants; and these instants