Zeno

Russell doesn't mention Zeno at all although he is perhaps nowadays one of the best known pre-socratics, due to his paradoxes. His paradoxes are of the type that typifies a certain kind of logical smart-arsery of the "If a tree falls down in a forest......" variety. They're amusing diversions that don't really lead anywhere.

Zeno was a disciple (and reportedly also lover) of Parmenides and shared his penchant for tying himself in logical knots. His series of arguments were in support of Parmenides' doctrine that "all is one" and that the common belief in plurality and change is mistaken, and in particular that motion is nothing but an illusion. Supposedly there were forty arguments in total but only a few have survived.

A thorough exploration is here: Stanford
And a simpler one here: Wikipedia