《宋史·本纪·卷三十六》
承相虞允文又请求立太子，孝宗说： 肤一旦确立太子，即令亲王出镇外藩，你应该讨论前代典礼。 
丞相允文复以请，孝宗曰： 朕既立太子，即令亲王出镇外藩，卿宜讨论前代典礼。 
Prime Minister Yu Yunwen then asked for the crown prince to be established, and Emperor Xiaozong said: If I were to establish the crown prince at once, then this will cause the imperial princes to garrison outside regions, and you should discuss the regulations of previous dynasties. 
<s>[INST] Identify the key themes in this Classical Chinese text and explain them in English: 丞相允文复以请，孝宗曰： 朕既立太子，即令亲王出镇外藩，卿宜讨论前代典礼。  [/INST] Prime Minister Yu Yunwen then asked for the crown prince to be established, and Emperor Xiaozong said: If I were to establish the crown prince at once, then this will cause the imperial princes to garrison outside regions, and you should discuss the regulations of previous dynasties. </s>
Identify the key themes in this Classical Chinese text and explain them in English: 丞相允文复以请，孝宗曰： 朕既立太子，即令亲王出镇外藩，卿宜讨论前代典礼。
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Prime Minister Yu Yunwen then asked for the crown prince to be established, and Emperor Xiaozong said: If I were to establish the crown prince at once, then this will cause the imperial princes to garrison outside regions, and you should discuss the regulations of previous dynasties.
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