When the position of a heavenly body changes with such extreme slowness as to leave astronomers undecided as to the change even, and still more as to the direction of the change, it is their custom to compare two observations made at a great interval of time. If the doubt still exists, they affirm with certainty that the position they have measured is invariable, or nearly so, since it is subject to no regular and persistent alteration. Such a method applied to the history of the human mind leads to grave melancholy and discouragement. Men have been ignorant and blind at every epoch. Always we find the same ignorance, the same rash illusions, the same obstinate prejudices.
Toujours mêmes acteurs et même comédie.
Three centuries before our era, a philosopher, Cleanthes, demanded that Aristarchus should be brought to justice for his blasphemies in declaring the earth in motion, and the sun to be the fixed centre of the universe. Two thousand years later, the human understanding had not progressed. The desire of Cleanthes was realized, and Galileo was accused of blasphemy and impiety, in his turn. A tribunal dreaded by all condemned his writings, constrained him to denials disavowed by his conscience, and, judging him unworthy of a freedom that he had abused, deprived him of a part of it, and thought it an indulgence to have left him any liberty whatever.
But history is not to be judged in this way. Events in themselves are of small moment; the impression that events produce is the only revelation of the public consciousness. Never before has its generous aversion for intolerance burst forth so strongly as for the sufferings of Galileo. The story of his misfortunes, exaggerated like a pious legend, has confirmed the triumph of the truths for which he suffered, at the same time avenging him. The scandal of his condemnation will forever vex the pride of those who still wish to put down reason by force; and the just severity of opinion will preserve the unwelcome remembrance as an eternal reproach. But it is necessary to be frank: this great lesson did not cause any deep sorrows. The long life of Galileo, taken all in all, is one of the most peaceful and most enviable that the history of science records.
The foregoing paragraphs translated freely from the life of Galileo by M. Bertrand, perpetual secretary of the Paris Academy of Sciences, expresses so precisely the point of view of this article that I have quoted them in order to have, from the outset, the support of his great authority. And to them may be added the following extracts from the 'History of the Inductive Sciences' of Dr. Whewell, master of Trinity College, Cambridge. The words in brackets are my own.