The Fault in Our Stars (2014)
Willem Dafoe: Peter van Houten
Van Houten : [On the book 'An Imperial Affliction'] Pain demands to be felt.
Van Houten : Let's imagine you are racing a tortoise, the tortoise has a 10 yard lead in the start, and in the time it takes you to run 10 yards, the tortoise's moved maybe one yard. So alright, you're faster than the tortoise but you cannot never catch it, you can only decrease his lead. Now certainly you can run past the tortoise as long as you don't contemplate the mechanics of that, but the question of how turns out to be so complicated that no one really solved it until Cantor proved that some infinities are bigger than other infinities... I think that answers your question.