13. It is necessary to banish from chimerical hypothesis the possibility of the encounter of the Earth with another planet. The regularity and unchangeableness of the laws which preside over the movements of celestial bodies take away all probability of a collision between them.
The Earth, however will have an end; but how? This is something upon which it is impossible to decide; but, as it is far from the perfection to which it will attain, and from the decay which will be a sign of its decline, its present inhabitants may well be assured that it will not be in their time (chap. VI, from item n° 48 on).