元代以來，學者多認為朱子是疑《古文筒書》偽作的先聲。他們認為，朱子首先由文體的難易上懷疑古文偽作，也就是說，朱子感覺到今文皆艱澀而古文反平易，從而懷疑平易的古文是晚出的偽作。本文以為，這是以後代辨偽的觀念，離開朱子的脈絡而誤讀的結果。在朱子的脈絡中，「平易」與「艱澀」另有其意義，是在「讀書能不能領會道理」的關懷下，所產生的問題，與辨偽並不相干。因此，朱子每每在質疑何以今文皆艱澀而古文皆平易之後，要學生「只揀其中易曉底讀」，並要人「沈潛反復乎其所易1，他所看重的反而是平易的古文。再就宋代的《筒書》學環境而書，本文舉出朱子同時及稍前稍後的學者，對於今、古文難易問題的思索，證明從當時對今、古文《筒書》的背景知識以及解決問題的思考方向看，宋代學者並沒有懷疑《古文筒書》偽作，當時學者在區分了今、古文難易二體之後，比較不滿意的反而是艱澀的今文，他們致力於解釋何以今文艱澀的問題，而不是懷疑平易的古文為晚出偽作。本文也嘗試追溯「朱子懷疑古文偽作說」的源流，對《古文筒書》辨偽史的片斷提出另一種解釋架構。 It is generally held that Chu Hsi was the originator of the doubt on the authenticity of the "ancient script"portion of the Book of Docume-nts. How-ever, this claim was entrenched as truth as a result of the repetition of an error made by Wu Ch'eng(1249-I333).Wu misinterpreted Chu Hsi's state-ments on the "ancient script" portion out of context and read his own suspi-cion into Chu's sentences. In this paper,l am going to prove that even though Chu did sense some stylistic problems of the Book of Documents as a text,he felt the "modern script" was difficult to read while the "ancient script" was rather easy to follow, but he did not thereby question the authenticity of the "ancient script" portion. Moreover,his uncertainty regarding the Book of Documents was not confined to the "ancient script" portion and was in fact expressed as a concern more for the "modern script" than for the "ancient script"portion because of the particular difficulty of the language used in the "modern script" portion. For this reason,he emphasized the value of the "ancient script" portion and counselled his students to focus on passages with "clear meaning"and to "hold" them "closely in one's self for experien-tial savouring". The two terms,"smooth and easy"(p'ing-i) and "difficult and harsh" (chien-se),are totally irrelevant to forgery detection. Furthermore,l will expound it was impossible for Chu Hsi to doubt the authenticity of the ancient script texts under the discourse of Sung studies on the Book of Docu-ments. Chu Hsi's fellow scholars and disciples did not take his perplexity about the stylistic problems to be an indication of Chu Hsi as a doubter of the "ancient script"portion of the Book of Documents.