According to Aristotle, Thales thought that the earth rests on water:

This [opinion that the earth rests on water] is the most ancient explanation which has come down to us, and is attributed to Thales of Miletus (Cael. 294 a28-30).

By using this idea/law Thales was able to explain earthquakes; earthquakes happen because of the fluctuation in water on which earth rests.

This is the only phenomenon which, I found, was explained by the law of floating Earth. Are there any other phenomena which are explained by this 'watery' law? If yes, then please also post sources. If not, then why?

Thales, as the legends say, was a genius, who predicted solar eclipse (I don't believe this), became rich by his knowledge of astronomy. Then why did he believe the idea that 'earth rests on water' by just one phenomenon which he explained by it? It doesn't seem justifiable that a genius like Thales believed in a trivial law just because it can explain a single phenomenon!

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    Do you know about Presocratic philosophers ? There are no extant works by Thales; "the doxographical reports say that Thales did not write a book. Aristotle's comments do not sound as if they were based on first-hand knowledge of Thales' views." This means that, if already in A's time the knowledge about Thales' theories was second-hand, it it quite useless to speculate today about "details". Commented Apr 14, 2020 at 13:11
  • A scholarly work on Thales's life and philosophy is O'Grady Thales of Miletus. You can find some educated guesses about what he thought there.
    – Conifold
    Commented Apr 14, 2020 at 22:35
  • 'why did he believe' you are asking for opinions or speculating on history. Please read forum rules. Commented Apr 15, 2020 at 4:59

1 Answer 1


Thales proposed that everything is water. So there are two reasons to guess that the land floats on the waters before the idea that earthquakes are because of waves in that underlying water.

Ice is the natural solid form that is made of water. So, on average, solids should be lighter than water, like wood -- what remains to be explained is why there would be any solids heavier than water, and why we encounter mostly those. Presumably Thales offered a solution there that is lost to history, or everyone should have just written him off right there.

The land we encounter also lies above the sea, and we see the water flows into the earth and disappears after it rains. So there should be huge reservoirs of water under the land. This predates the idea that the water is pumped back up into the sky in some way. It is not hard to imagine, between the seas and the idea there is water under the land, that the whole of the land floats on the water. (Or with minor variation that the whole sky and Earth are in a bubble underwater. But that still means the land lies over water, which fills the whole of the rest of the universe.)

Both of these ideas seem to have also occurred to early generations of Biblical scholarship: the one to explain how the water comes before the land in order of creation, in commentaries on Genesis; the other to address why a seemingly infinite amount of water can fall out of the sky and we don't all drown, in commentaries on Ecclesiastes.

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