way along the vistas
opened up by the geologists. We look through the protracted tertiary
ages, when mighty animals, now generally extinct, roamed over the
continents. Back still earlier through those wondrous secondary
periods, where swamps or oceans often covered what is now dry land,
and where mighty reptiles of uncouth forms stalked and crawled and
swam through the old world and the new. Back still earlier through
those vitally significant ages when the sunbeams were being garnered
and laid aside for man's use in the great forests, which were
afterwards preserved by being transformed into seams of coal. Back
still earlier through endless thousands of years, when lustrous
fishes abounded in the oceans; back again to those periods
characterized by the lower types of life; and still earlier to that
incredibly remote epoch when life itself began to dawn on our
awakening globe. Even here the epoch of our present history can hardly
be said to have been reached. We have to look through a long
succession of ages still antecedent. The geologist, who has hitherto
guided our view, cannot render us much further assistance; but the
physicist is at hand--he teaches us that the warm globe on which life
is beginning has passed in its previous stages through every phase of
warmth, of fervour, of glowing heat, of incandescence, and of actual
fusion; and thus at last our retrospect reaches to that particular
period of our earth's past history which is specially illustrated by
the modern doctrine of Time and Tide.

The present is the clue to the past. It is the steady application of
this principle which has led to such epoch-making labours as those by
which Lyell disclosed the origin of the earth's crust, Darwin the
origin of species, Max Mueller the origin of language. In our present
subject the course is equally clear. Study exactly what is going on at
present, and then have the courage to apply consistently and
rigorously what we have learned from the present to the interpretation
of the past.

Thus we begin with the ripple of the tide on the sea-beach which we
see to-day. The ebb and the flow of the tide are the present
manifestations of an agent which has been constantly at work. Let that
present teach us what tides must have done in the indefinite past.

It has been known from the very earliest times that the moon and the
tides were connected together--connected, I say, for a great advance
had to be made in human knowledge be