《定势》是《文心雕龙》第三十篇。什么叫定势,需要分开来说。先说势。这篇里打了个比方,叫“润曲湍回”,溪身曲折,河床又陡,所以水流又急又回旋;要是溪身直,河床坦,水流就会又缓又直。溪身有曲有直,河床有陡有坦,如同文章的体裁有章表奏议,有赋颂歌诗,有符檄书移,有史论序注。溪水有回旋,有直流,有急有缓,如同文章有的典雅,有的清丽,有的明断,有的核要。造成溪水的或回旋,或直流,或急或缓,是由于溪身有曲有直,河床有陡有坦, “Set” is “Wen Xin Diao Long” thirtieth. What is the trend, you need to say separately. First potential. This article called an analogy, called “Ruqu song turbulent back,” twists and turns stream, the riverbed is steep, so the water flow and anxious and convoy; if the river straight body, the river bed Tan, water will be gentle and straight. Creek has a song straight, steep and smooth river bed, as the style of the article chapter table is played, there are eulogizes poetry, there is Fuxian book shift, the history of preface Note. Streams have maneuvering, there are DC, there is an urgency and ease, as the article some elegant, some elegant, some cut off, and some nuclear. Caused by streams or maneuvering, or DC, or urgent or slow, is due to the song has a straight body, the river bed is steep,