In the first half of the 17th-century Polish literature succumbed to a wave of plagiarism, which ranged from crude appropriation of authorship or the ransacking of whole passages from someone else's text to the uninhibited production of various compilations, adaptations, and cryptoquotes. One of the most prolific plagiarists was Jan Karol Dachnowski, who published under his own name Jan Zabczyc's collection of carols 'Angelic symphonies'. This article identifies another of Dachnowski's plagiarisms. It is the mystery poem 'Dialogue about the wondrous nativity of the Son of God' (1621). More than half of that poem, so far regarded as Dachnowski's original work, was in fact copied verbatim from Grzegorz Czaradzki's 'Rhymes on the immaculate birth by the the Virgin Mary, Mother of God' (1613). What makes this 'borrowing' even more astounding is the fact that Czaradzki's poem happens to be a translation of 'De partu Virginis' by the celebrated Renaissance poet Jacopo Sanazzaro.