In the preface, Chesterton specifies his goal for the book: to explain how he personally established his faith in his personal theology.He begins by explaining that human nature seems to betray itself. On the one hand, humans feel a strong desire to explore, to learn, and to grow through journeying into the unknown. On the other hand, humans feel a need for security and safety. He explains that sanity contains both sets of emotions. Chesterton explains that Christianity is a suitable belief system to mitigate the effects of that paradox.