Affekt概念盛行於17、18世紀的音樂演奏領域，其含義為音樂家透過不同的手法傳遞其音樂，進而激發及提升聽眾之情感。在眾多18世紀音樂教學文獻及樂譜當中，Affekt一詞被當代音樂家及理論家大量使用，即可知其意義重大及影響之深遠。然而，此理論於18世紀中葉過後漸漸不被使用，直到今日。本論文以巴赫E小調小提琴與數字低音奏鳴曲（BWV 1023）為例，透過雷歐波德‧莫札特小提琴教學法以及其他18世紀中葉當代教學文獻，藉由史學的角度，深入探討Affekt在18世紀的樂曲中，如何詮釋並運用在音樂上。綜合整理其分析及討論，可以得知Affekt與音樂風格、速度、節奏等音樂技巧息息相關。音樂家應透過適當且正確的音樂性及技巧性傳達Affekt，以呈現良好的音樂品味及正確的音樂實踐。

Originated in the late 16th century, the concept of “Affekt”, which gradually became popular in music performance in the 17th and 18th centuries, designates emotions which a musician seeks to stir among listeners through the use of rhetorical figures as applied to music. Indeed, the term “Affekt” was constantly found in a wide range of musical treatises as well as in scores, most often as a tempo marker, so it exerted great influence during this time. However, the term began to disappear after the mid-18th century, in tandem with the development of the classical style. Since then, “Affekt” became almost obsolete and has rarely been mentioned in the context of music performance practice. This article traces the historic development of “Affekt” and discusses the interpretation of Violin Sonata in E minor (BWV 1023) by J. S. Bach from the theories of “Affekt” proposed by Leopold Mozart in his Versuch einer gründlichen Violinschule, as well as the works by Mozart’s contemporaries. Through discussion and analysis on selected literature and performances, the author also investigates the extensive passages that the 18th-century theorists and musicians used to categorize the types of “Affekt” and their impact on style, tempo, rhythm, overall music movements and more in their theoretical writings. In order to employ the appropriate styles of “Affekt” and achieve a historically-informed execution of 18th-century music, the musician should therefore familiarize themselves with the expression and manner of performance both technically and musically in order to achieve the emotional effects intended by the composer.