Tremellius' 1569 edition of the Syriac New Testament was a quite distinctive product of Heidelberg oriental scholarship, very different from other sixteenth-century editions produced by Catholic scholars. Tremellius produced his edition by first reconstructing an historical grammar of Aramaic and then, in the light of this, vocalising the text of Vat. sir. 16 which he took to be more ancient than that of Widmanstetter's editio princeps. Thus in this way he sought to construct the earliest recoverable linguistic and textual form of the Peshitta. The anonymous Specularius dialogus of 1581 is here used for the first time to corroborate this assessment of Tremellius' achievement and to cast light on the confessional polemics his edition provoked.