句子通过对比At fifty和forty-nine years before，突显了时间跨度带来的认知觉醒。
In his later years, Beethoven once listened to a friend play his "Thirty-two Variations in C minor." After listening for a while, he asked, "Who composed this?"
"You did," his friend replied.
"Me? Could I have written such clumsy music?" Beethoven then added, "Ah, Beethoven used to be a fool!" Goethe's comment on Schiller applies perfectly to Beethoven: "He changes and grows every week." Every time I saw him, I felt his knowledge, learning, and insights had improved since the last time."
There was a period when Beethoven even wanted to destroy the songs "Adelaide" and the "Trio in E-flat Major" (Op. 20) that he had composed in his youth. This was by no means accidental; like Beethoven, one can truly say, "At fifty, I knew the errors of the forty-nine years before."
晚年的贝多芬曾听一位朋友弹奏他的《c小调三十二变奏曲》。听了一会儿，他问道：“这是谁的作品?”
“你的。”朋友回答说。
“我的?这么笨拙的曲子会是我写的?”贝多芬随后补充道：“啊，当年的贝多芬简直是个傻瓜!”歌德评论席勒的话，完全适用于贝多芬：“他每星期都在变化，在成长。”我每次看到他时，总觉得他的知识、学问和见解比上一次进步了。”
有一时期，贝多芬甚至想毁掉他青年时期所作的歌曲《阿黛莱苔》和《降E大调七重奏》(作品20号)。这决不是偶然的，像贝多芬这样，真可以说是“五十而知四十九之非”了。
"To admit a mistake is to have already corrected half of it."
"The most difficult task is to evaluate oneself."
"If you want to know what others say about you behind your back, first examine how you speak of others"
"We often believe ourselves to be noble, just, or kind."
"Even the wisest struggle to abandon the weakness of pursuing fame."