Based on the example of the Apologia by Nicholas of Dresden, a treatise written in July 1415 as a reaction to the prohibition of the lay chalice issued by the Council of Constance, the article discusses certain aspects and difficulties of textual criticism. It presents several so far unstudied manuscript details that may help discover valuable information about the function of the texts and their later reception. It also examines the limits of textual criticism and the problems of constructing a stemma of theological texts with a rich textual tradition. It shortly discusses certain orthographical peculiarities which are traditionally disregarded in critical editions, but which can - upon closer examination - reveal valuable details about the author and the function of the text.