Hi, I'm Peter Adamson, and you're listening to the History of Philosophy podcast, brought to you with the support of the philosophy department at King's College London and the LMU in Munich,

online at historyof philosophy.net.

Today's episode, Indivisible Under God, the Revival of Atomism.

One thing you need to learn as a baby is that physical objects don't just banish into thin air.

And one thing you need to learn when you get older is that sometimes they do.

I don't just mean the magician's assistant who vanishes after stepping into a box on a stage.

The young child might observe a puddle on her way to kindergarten,

and then notice that it's gone when she's heading home at lunchtime,

affronted by this violation of the entirely reasonable laws that have otherwise been governing the

universe, she might ask her mother where the puddle has gone.

Oh, the mother will say, it evaporated.

Only much later will the child understand what this means once she finally reads Aristotle

on weather phenomena.

He explains that water on the surface of the earth transforms into moist exhalations,

which then condense into cloud.

Saturated clouds in turn produce rain, which is where we get the puddles in the first place.

So, Mom knew what she was talking about.

Aristotle's exhalation is really just the same as the

vapor contained within the word, evaporation. Plausible, though this sounds, our former

kindergarten child may press for more information, asking how and why the water in the puddle just

changes itself into vapor without a single magician in sight.

Aristotle and his followers would say that it is because the four elements mutually transform

...