《北史·列传·卷二十八》
虽然也曾有帝王这样作，暂时又被沿袭，然而怎么能将帝王们一时的恩泽当成万世不变的成规呢？ 
虽复帝王制作，弗相沿袭。然一时恩泽，岂足为长世之轨乎。 
"Although there were emperors who acted in this way, and others followed suit, how can we take the occasional favor of emperors as perpetual rules?"
<s>[INST] Identify the key themes in this Classical Chinese text and explain them in English: 虽复帝王制作，弗相沿袭。然一时恩泽，岂足为长世之轨乎。  [/INST] "Although there were emperors who acted in this way, and others followed suit, how can we take the occasional favor of emperors as perpetual rules?"</s>
Identify the key themes in this Classical Chinese text and explain them in English: 虽复帝王制作，弗相沿袭。然一时恩泽，岂足为长世之轨乎。
user
"Although there were emperors who acted in this way, and others followed suit, how can we take the occasional favor of emperors as perpetual rules?"
assistant