Full Idea
The arrow paradox starts with the assumption that space and time are atomic; the tortoise starts with the opposite assumption that space and time are infinitely divisible.
Gist of Idea
Space and time are atomic in the arrow, and divisible in the tortoise
Source
Keith Devlin (Goodbye Descartes [1997], Ch. 2)
Book Reference
Devlin,Keith: 'Goodbye Descartes: the end of logic' [Wiley 1997], p.24
A Reaction
Aquinas similarly covers all options (the cosmos has a beginning, or no beginning). The nature of movement in a space which involves quantum leaps remains metaphysically puzzling. Where is a particle at half of the Planck time?