In book 2, chapter 19, Molanus discusses how one should deal with artworks depicting matters from unestablished textual traditions. Foremost is that no false stories are depicted, but in the case of artworks based on uncertain stories, propriety and probability should prevail in the judgement and above all the common opinion of the whole Church.
The second example of such an iconographic tradition surrounded by uncertainty in the Scriptures is the means of travel during the Flight into Egypt by the Holy Family. Molanus assesses the current pictorial tradition and concludes that the depiction of the Virgin Mary on a donkey with Christ in her arms and Joseph next to them on foot corresponds to the travelling habits of that period.
“Again, one can depart from probable conjunctures to paint the flight into Egypt, about which the Evangelist remains silent. It is likely, that the fragile Virgin carrying Christ in her arms could not have completed such a long journey on foot. So the painters give her a mount, the kind that was customary among the poor, and which, neither prancing nor galloping, is in the habit of tiring either itself or the person riding it. As for Joseph, the leader of the expedition ordered by the angel, accustomed to the work of a craftsman, they represent him as a pedestrian, since the parents of God lived in great poverty to which the accounts of the birth and presentation of the Lord bear witness, and it does not seem conceivable that they could have bought two mounts.”
“Rursum, in fuga Christi ad Aegyptum depingenda, quod Evangelista tacuit, pictor ex probabili coniectura supplere debuit. Probabile vero est quod tenera virgo puerum Iesum baiulans, vastum illud itineris spatium ambulando non potuerit absolvere. Itaque pictores dant ei iumentum quo pauperiores uti solent, quocque nex se nex sessorem suum aut saltando aut sestinando fatigare solet. Iosephum autem, qui ex mandato Angeli dux erat itineris et laboribus sabrilibus affuetus, ideo pedestrem pingunt, quia magna illa Dei parentum paupertas quae nobis in historiis nativitatis et praesentationis Domini declaratur, non videtur admittere potuisse duorum iumentorum sumtus.”
Molanus 1996, 176.