taught that the stars stood out at unimaginable distances in the
ocean of ether, and imagined the ether as stirring in gigantic
whirlpools, which bore cosmic bodies in their orbits as the eddy
in the river causes the cork to revolve.

These stimulating conjectures made a deep impression on the new
age. A series of great astronomers had meantime been patiently
and scientifically laying the foundations of our knowledge.
Kepler (1571-1630) formulated the laws of the movement of the
planets; Newton (1642-1727) crowned the earlier work with his
discovery of the real agency that sustains cosmic bodies in their
relative positions. The primitive notion of a material frame and
the confining dome of the ancients were abandoned. We know now
that a framework of the most massive steel would be too frail to
hold together even the moon and the earth. It would be rent by
the strain. The action of gravitation is the all-sustaining
power. Once introduce that idea, and the great ocean of ether
might stretch illimitably on every side, and the vastest bodies
might be scattered over it and traverse it in stupendous paths.
Thus it came about that, as the little optic tube of Galilei
slowly developed into the giant telescope of Herschel, and then
into the powerful refracting telescopes of the United States of
our time; as the new science of photography provided observers
with a new eye--a sensitive plate that will register messages,
which the human eye cannot detect, from far-off regions; and as a
new instrument, the spectroscope, endowed astronomers with a
power of perceiving fresh aspects of the inhabitants of space,
the horizon rolled backward, and the mind contemplated a universe
of colossal extent and power.