今人演奏古琴曲《廣陵散》，多採現代定義而將「擘」彈成「向內入弦」。然考查古譜，論及「擘」者，或以出弦言之，始見於隋、唐之際的《烏絲欄》，後 來唐代的趙耶利、陳拙、宋代的《則全和尚節奏指法》、《事林廣記》繼之；或以 入弦言之，可以上溯至唐末劉籍的《琴議》，再見於元代吳澄的《琴言十則》。到 了明代，兩種主張紛雜並陳；在清代，前者漸漸式微，後者則為較多且重要的琴 譜所記載，於是取代了前者，成為現今琴壇的主流。 關於兩種指法定義相歧的原因，《琴學心聲諧譜》認為是諸家對「內」、 「外」標準不一所致；然而，在宋、元、明代的琴譜中，雖有「擘出托入」與 「擘入托出」的不同，但提到「內」、「外」、「出」、「入」的標準，都是相同的。 由此可知《心聲》的論證之誤；歧異的原因，也只能歸咎於減字譜發展過程的不 夠嚴謹精確所致。 擘的出弦與入弦兩種彈法的差異，在演奏實務上，影響較大是「歷擘」的套 頭指法。「歷擘」常出現於唐、宋流傳下的琴曲，但「擘」的兩種定義出現的時 代都不能算晚，不可單純地用古、今指法來做為區分的標準，因此「歷擘」中 的「擘」的方向，還要有更多資料來佐證。現存同時具備「歷擘」與「擘」兩種 指法解釋的琴譜並不多見，筆者僅找到隋、唐之際的《烏絲欄》與宋代的《太古 遺音》中的「楊祖雲指法」，兩個譜本都是以「出弦」來定義「擘」的方向，故 可以確定「歷擘」是食指向外彈出兩弦後，大指隨即亦向外彈出一弦。這樣的彈 法很調適順遂，正可以糾正時下琴壇「以今律古」的錯誤彈法。

Present-day guqin musicians mostly adopt the modern definition of the fingering bo, i.e. the thumb technique of plucking inwards, when they interpret the piece Guangling San. However, historical scores suggest that discrepancies exist in the fingering’s definitions: bo as “thumb plucking outwards” can, at the earliest, be traced back to Wusi Lan published between the Sui Dynasty and the Tang Dynasty, which was followed by Zhao Ye-li and Chen Zhuo in the Tang Dynasty, and then Zechuan Heshang Jiezou Zhifa and Shihlin Guangji in the Song Dynasty; alternatively, bo as “thumb plucking inwards” dates back to the late Tang dynasty in Liu Zi’s Qin Yi, which reappeared in Qinyan Shi Ze by Wu Cheng in the Yuan Dynasty. The two opposite views used to each own supporters in the Ming Dynasty. In the Qing Dynasty, the latter (inwards) gradually outnumbered and replaced the former (outwards) by the majority of its presence in prominent scores. Bo as thumb plucking inwards has since become the mainstream standard of the fingering until today. As to why such a striking discrepancy exists, Qinxue Xinsheng Xiepu asserts that it results from different schools’ divergent standards for fundamental definitions of inwards vs. outwards. However, in historical scores from the dynasties of Song, Yuan, and Ming, the standards for inwards vs. outwards were consistently the same. This proves Qinxue Xinsheng Xiepu’s argument to be unfounded. Therefore, the discrepancy could be ascribed, if at all, to the lack of precision in the development of jianzi pu (reduced notation). In practice, the discrepancy between definitions of the fingering bo as inward and outward matters most when it comes to the compound fingering libo, which appears often in pieces that date back to the Tang Dynasty and the Song Dynasty. However, the two divergent definitions of bo can both be traced back rather early, thus overturning the attempt to assess and distinguish between the two definitions by which emerged first. It is, therefore, necessary to call upon more archival evidence to verify bo’s inward or outward direction in libo. Extant scores that include definitions of both bo and libo are rare, among which Wusi Lan published between the Sui Dynasty and Tang Dynasty and the “Yang Zu-yun’s Fingerings” noted in Taigu Yiyin from the Song Dynasty are two primary sources that the author has been able to find so far. In both scores, the direction of bo is defined as outwards. I would, therefore, posit that libo refers to the fingering of the thumb’s outward plucking that follows the index finger’s double outward plucking. In this definition, the fingering can be executed smoothly. Based on the investigation in this paper, I would like to further argue that the investigation into the fingering bo is also where the biased interpretation of the fingering ought to be pointed out, as such a bias is but a result of the inclination to “discipline the past with the present” that prevails in the contemporary guqin circle.