A Guide to Stoicism 5 ¶19 — St. George Stock (modern guide)

St. George Stock (modern guide), A Guide to Stoicism 5 ¶19

The tendency of all things in the universe to the centre kept the earth fixed in the middle as being subject to an equal pressure on every side. The same cause also, according to Zeno, kept the universe itself at rest in the void. But in an infinite void, it could make no difference whether the whole were at rest or in motion. It may have been a desire to escape the notion of a migratory whole which led Zeno to broach the curious doctrine that the universe has no weight, as being composed of elements whereof two are heavy and two are light. Air and fire did indeed tend to the centre like everything else in the cosmos, but not till they had reached their natural home. Till then they were of an upward-growing nature. It appears then that the upward and downward tendencies of the elements were held to neutralise one another and to leave the universe devoid of weight.