《颜氏家训·养生篇》
再认真考查内教，即使能成仙，最终还是会死去，无法真正的摆脱人世间的羁绊而长生。我不愿意让你们专心致力于此事。
考之内教，纵使得仙，终当有死，不能出世，不愿汝曹专精於此。
After careful examination of the inner teachings, even if one can become an immortal, one will eventually die and will not be able to truly break free from the fetters of the world and live forever. I don't want you to dedicate yourself to this.