《背德者》与《窄门》堪称纪德小说创作中的"双璧"，其原因在于两部作品各自的主人公在道德问题上体现了截然相反的对称倾向：《背德者》的主人公为了追求官能的享受而背弃道德，《窄门》的主人公则为了保持完美春节的德行而坚拒尘世的欢乐与人间的幸福。纪德以极大的勇气深刻地揭示出自己思想中尖锐而深刻的矛盾，以无所畏惧的对真理的热爱，并以敏锐的心理学洞察力，呈现出人性的种种问题与处境。(The Immoralist and Strait Is the Gate are regarded as the two sides in Gide's novels, because the protagonists of two works embody the diametrically opposite symmetry tendency in terms of morality. The protagonist of The Immoralist abandons the morality for the sake of pursuing the enjoyment of sense, while the protagonist of Strait Is the Gate insists on rejecting earthly happiness for maintaining the virtue of purity and perfection. Gide reveals the sharp and profound contradictions in his thoughts with great courage, and presents human issues and situations with fearless passion for truth and keen psychological insight.)