De Rerum Natura - Lucretius' Physics

Lucretius' Physics

Lucretius maintained that he could free humankind from fear of the gods by demonstrating that all things occur by natural causes without any intervention by the gods. Historians of science, however, have been critical of the limitations of his Epicurean approach to science, especially as it pertained to astronomical topics, which he relegated to the class of "unclear" objects.

Thus, he began his discussion by claiming that he would

explain by what forces nature steers the courses of the Sun and the journeyings of the Moon, so that we shall not suppose that they run their yearly races between heaven and earth of their own free will or that they are rolled round in furtherance of some divine plan....

However, when he set out to put this plan into practice, he limited himself to showing how one, or several different, naturalistic accounts could explain certain natural phenomena. He was unable to tell his readers how to determine which of these alternatives might be the true one.

Let us now take as our theme the cause of stellar movements.

• First let us suppose that the great globe of the sky itself rotates....
• There remains the alternative possibility that the sky as a whole is stationary while the shining constellations are in motion. This may happen

• because swift currents of ether ... whirl round and round and roll their fires at large across the nocturnal regions of the sky. Or
• an external current of air from some other quarter may whirl them along in their course. Or
• they may swim of their own accord, each responsive to the call of its own food, and feed their fiery bodies in the broad pastures of the sky.

One of these causes must certainly operate in our world.... But to lay down which of them it is lies beyond the range of our stumbling progress.

Drawing on these, and other passages, William Stahl considered that "The anomalous and derivative character of the scientific portions of Lucretius' poem makes it reasonable to conclude that his significance should be judged as a poet, not as a scientist."