漢末以降，書法逐漸走向多元時代，不僅裝、隸持續發展，草、行亦躍上歷史舞台，書法理論也成為書法家探究的一門學問。魏晉時期，是書法自覺的時代，書法已從實用的目的，昇華至藝術的境界，成為文人品評欣賞的專門藝術。在門閥意識高澈的時代，書法是上層社會的權力象徽，世族是最有機會從事書法創作的階層，因為家族間的交流，使筆法能夠相傳，因此，此時期的書法家多是世族子弟。衛恒〈四體書勢〉是探討古文、筆書、隸書、草書的書學理論，其行文先文後贊，內容包括文字起源、字形的喻象描寫以及筆法技巧的論述，其中也保存西晉以前的書法家俠事，對於研究魏晉書法者提供佐證的機會。筆者以為，書法理論絕非僅是字形喻象的描寫而已，筆法技巧因難以言喻，是故鮮少為人所論，本文試圖就比髮部份進行分析，冀能解讀前人所未發之筆法含意。

After the end of the Han dynasty, the calligraphy headed for the times of diversity gradually. Not only did seal script and clerical script kept on evolving, cursive and semi-cursive script also went on the stage of history. The theories of calligraphy also become the kind of the knowledge on which calligraphists work. The Wei and Jin times was the period that the calligraphy was aware of itself .Calligraphy had already turned from the practical purpose, sublimating in the realm of art and became the scholars' class to an special art for criticizing and for appreciating. At a time when the awareness of upper-class family surged, the calligraphy was a symbol of power of the upper-class society. Those people coming ftom the upper-class families had the most opportunities to work on calligraphy creations. And exchanges between them made it possible for the style of writing to be passed on to their offspring. Therefore, calligraphists at that time were mostly males of upper-class families. Wei Heng's＂ Si Ti Shu Shi＂ is a book which studies the theory of ancient text, seal script, clerical script and cursive script. ＂Si Ti Shu Shi ＂ 's writing method is that a text comes first then an explication follows. Its content includes words' origins, descriptions of the metaphors of shapes of words and elaborations on styles of writing techniques. Also, it records plenty of anecdotes of the calligraphists of Western Jin times and provides substantial evidence for future calligraphy researchers. This thesis's conclusion is that calligraphy theories are far from just descriptions of the metaphors of the shape of words. The style of writing techniques are difficult to delineate so is has rarely been discussed. This thesis tries to carry on the analysis for the style of writing with the hope of finding out new meanings of the style of calligraphy writing which what our calligraphy researchers before had not found.