《月亮与六便士》的英文经典句子可归纳为以下五类，结合权威来源整理如下：

关于人性本质

- "The average person is not the kind of person they want to be, just the kind of person they have to be."（普通人并非他们想成为的人，而是不得不成为的人。）

- "A man is not what he wants to be, but what he has to be."（人并非想成为的那样，而是被迫成为的那样。）

孤独与沟通困境

- "We are all alone in the world."（我们每个人生而孤独。）

- "He is shut in a tower of brass, and can communicate with his fellows only by signs, and the signs have no common value..."（他被困在铜塔中，只能通过无意义的符号与同伴交流。）

理想与现实的冲突

- "Chasing a dream is chasing his own bad luck."（追逐梦想就是追逐厄运。）

- "The ground was six pence, but he looked up and saw the moon."（地上满是六便士，他却抬头仰望明月。）

艺术与情感的表达

- "Art is the expression of emotion."（艺术是情感的宣泄。）

- "Art is not something that can be understood by only the educated."（艺术并非仅能被受过教育者理解。）

对社会的批判

- "We seek pitifully to convey the treasures of our heart, but they have not the power to accept them..."（我们可怜地试图向他人传递心中的宝藏，但他们无法接受。）

- "Rich同情心是一种迷人的本领，但有时会被滥用..."（过度的同情心可能适得其反。）

以上句子均出自毛姆原著或权威翻译，涵盖了对人性、艺术、社会等多维度的深刻洞察。