Age of Reason, Footnote 9

If it should be asked, how can man know these things? I have one plain answer to give, which is, that man knows how to calculate an eclipse, and also how to calculate to a minute of time when the planet Venus, in making her revolutions around the sun will come in a straight line between our earth and the sun, and will appear to us about the size of a large pea passing across the face of the sun. This happens but twice in about a hundred years, at the distance of about eight years from each other, and has happened twice in our time, both of which were foreknown by calculation. It can also be known when they will happen again for a thousand years to come, or to any other portion of time. As, therefore, man could not be able to do these things if he did not understand the solar system, and the manner in which the revolutions of the several planets or worlds are performed, the fact of calculating an eclipse, or a transit of Venus, is a proof in point that the knowledge exists; and as to a few thousand, or even a few million miles, more or less, it makes scarcely any sensible difference in such immense distances.

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