The presented analysis is based on the incunabulum Auslegung der heiligen Messe that was issued in 1495 and preserved until 1810 in the library of the Clarissan cloister in Wrocław. Now it is kept in the Library of the Wrocław University. We are given an interesting model of creating individual prayer based on contemplating common parts of a mass liturgy. The unkonwn author has derived most elements of his text from the mistique school of St. Bernhard, the abbey of St. Victor by Paris and the Dominican master Ekchardt, although he used the mistical treatises very freely. We can recognise the medieval German tradition of understanding liturgy in meditating every part of a mass by watching all gestures of a priest and keeping on oral supplicating. We are also given the aim of the prayer – cleansing of sinns and evil, earning a favour of the Holy Trinity and spiritual changing. The vision of a holy mass has been presented as the life and work of Jesus Christ but in fact we don`t find a distinct encourage to imitate the Saviour. The deep medieval tradition is shown in preventing from frequent receiving Holy Communion.