In reading this chapter, which I have not translated in full, one feels like an observer at work with a telescope out of focus. The thought of the Angelic Doctor is blurred by that fatal misconception which it was reserved for Newton to dissipate, that, in the heavens above, physical nature works necessarily and uniformly, but, on the earth beneath, contingently (so that the effect might be otherwise) and with some anomaly and irregularity. We must say boldly that the case is not so; that throughout all time and all space physical nature works necessarily and uniformly. The difference between astronomy and such sciences as chemistry and biology comes merely to this, that the elementary phenomena of astronomy, the orbits of the planets, and the rotation of the earth, depend, at first approximation, upon an extremely simple combination of causes, and therefore are readily calculable: whereas in the rest of nature complexity of causes and intermingling of effects is enormous, and our reckonings are continually thrown out by our ignorance of coexistences. The heavens are seen from a distance, and to the naked eye are visible only in their most general outlines. The earth would be a simple body enough to study with the naked eye ninety million miles away. Such an effect as the death by lightning of a sheep in a thunderstorm, which St Thomas would call 'contingent,' is really a complex physical effect, as necessary a part of the pre-established order of physical causation as the alternation of day and night. Positis ponendis, and leaving man out of the case, it is as impossible for that sheep to escape death as for the sun not to rise tomorrow: the only difference between the two cases is the multitude of ponenda. Cf. Chap. LXXIII, with notes.
Of God and His Creatures: 3.94