Replika M. Křišťana z Prachatic k proroctví M. Jana Pařížského

The main astronomical work of the Magister of Charles University Cristannus of Prachatice (after 1360-1439) are his two Latin treatises On the construction and On the use of the astrolabe. They were written for his university course in 1407. It has been proved that also the anonymous incunabula and old prints ascribed in the literature to Robert of Chester (Robertus Cestrensis, Anglicus) and Prosdocimo de Beldomandi (Perugia 1477-1479, 2nd ed. Venetiis 1497-1498 (1494?); Venetiis 1512, 2nd ed. Venetiis 1521), are in fact written by Cristannus of Prachatice. We present here the first edition of a small Cristannus' astronomical treatise supplementing his work in this field. It is a Latin paraphrase of the prophecy of Magister Iohannes Parisiensis and a Czech reply to it. The treatise is known in one manuscript only (Prague, National Library, XXII A 2, ff. 283r-287v). An autograph, written probably in 1422, is not preserved, a copy arose in or before the year 1525. Iohannes Parisiensis predicted the eclipses of the Sun and of the Moon on the August of the year 1422 and he deduced great disasters and catastrophes which are said to strike the Earth. Cristannus disagrees with his vision and he put in doubts both the data of the eclipse and of the constellations of the planets (i. e. astronomical facts) as well as the speculations about their possible consequences for the terrestrial events. Recalculating the data in the treatise we find that the Cristannus' predictions of the positions of the planets are not quite precise either, despite his results are better than those by Iohannes. However, first of all Cristannus refused the Iohannes' astrological interpretations and for this purpose he used both the scientific argumentation and the theological one. It seems also that Iohannes' prophecy was rather tendentious reaction on Hussitism than an astronomically well-informed text. Perhaps that is why Cristannus refused it: rather for the political and dogmatic reasons then due to its astronomically-astrological content and — maybe — that is why we can find some technical mistakes and possibly also wilful misunderstandings and falsifications in his reply.