Whether or not Zeno was merely trying to defend Parmenides from the ridicule of others, there is no doubt that he has pushed the analysis of reality onto a new plane. He makes us think not just about objects in space, but about space as a structure within which they exist; about motion not just as the behaviour of physical bodies, but as a theoretical concept involving conceptual divisions in space and time; about number not just as a way of counting finite bodies but as a rational system potentially (or actually) continuing ad infinitum, with the problematic consequences that that might entail; about the notions of 'before' and 'after' in time, and how long the duration of the present is.

Presocratic Philosophy: A Very Short Introduction (2004) - Ch. 3 : Zeno's tortoise