This can easily lead to contradictions and paradoxes. Types were created to prevent paradoxes, such as Russell's paradox. Donne's style is characterised by abrupt openings and various paradoxes, ironies and dislocations. Through poetry he also explores the paradoxes and complexities of this legacy. He also devoted much effort in refuting fallacies and paradoxes. This contradicts causality and leads to logical paradoxes. Philosophers question whether these paradoxes make time travel impossible. Many time travel works explore the topic of disrupting causality leading to time paradoxes. Axiomatic set theory was originally devised to rid set theory of such paradoxes. This leads to many of the well-known apparent "paradoxes" of relativity. It plays with some of the inherent paradoxes that would be caused by time travel. The ancient Greek philosopher Zeno of Elea gave several famous examples of such paradoxes. These feature impossible constructions, explorations of infinity, architecture, visual paradoxes and tessellations. There are reputed "paradoxes" that arise from failure to recognize this. Dr. Gillespie insists that time travel is impossible given the nature of temporal paradoxes.