the Aristotelian rather than the Hebrew teachings. Galileo's
death occurred in 1642, a hundred years after the death of
Copernicus. Kepler had died thirteen years before, and there
remained no astronomer in the field who is conspicuous in the
history of science as a champion of the Copernican doctrine. But
in truth it might be said that the theory no longer needed a
champion. The researches of Kepler and Galileo had produced a
mass of evidence for the Copernican theory which amounted to
demonstration. A generation or two might be required for this
evidence to make itself everywhere known among men of science,
and of course the ecclesiastical authorities must be expected to
stand by their guns for a somewhat longer period. In point of
fact, the ecclesiastical ban was not technically removed by the
striking of the Copernican books from the list of the Index
Expurgatorius until the year 1822, almost two hundred years after
the date of Galileo's dialogue. But this, of course, is in no
sense a guide to the state of general opinion regarding the
theory. We shall gain a true gauge as to this if we assume that
the greater number of important thinkers had accepted the
heliocentric doctrine before the middle of the seventeenth
century, and that before the close of that century the old
Ptolemaic idea had been quite abandoned. A wonderful revolution
in man's estimate of the universe had thus been effected within
about two centuries after the birth of Copernicus.



V. GALILEO AND THE NEW PHYSICS

After Galileo had felt the strong hand of the Inquisition, in