The whole work of natural science might be described under this phase; it has laid hold of the physical universe, and shown that the reality is unlike that which first appears. It has thus bred a fine, wholesome skepticism, which is the basis of true knowledge, and of progress. Once men said, This is as it appears; to-day they say, The reality is not according to the first appearance; but is probably the reverse. The sky seems solid; the sun seems to move; the earth seems to be at rest, and to be flat. Science has reversed these appearances and beliefs. But the Copernican revolution was simply the beginning of an endless process, and science has done little since but exchange Ptolemaic appearance for Copernican reality, and the process is commonly marked by reversal. The human mind tends to rest in the first appearance; Science—more than any other teacher—tells it that it may not.
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