Depicting the Carthusian monk Jan Vos (successively prior of the Charterhouses of Bruges and Utrecht) kneeling in prayer in front of the Virgin and Child, Petrus Christus' Exeter Madonna is a small painting probably destined to private devotional practices of its owner. This work is particularly interesting for it perfectly illustrates how the structuring of the pictorial space endows paintings that include devotional portraits with a dynamic dimension and how this dimension plays an essential role in the spiritual meaning and function of such images. The aim of this article is to show that by bringing together the worldly sphere below in the background and the sacred space in the foreground, where the Virgin welcomes the devotee, the Exeter Madonna can be understood as a visualization of the spiritual ascent of Jan Vos. To this end, the visual structure of the painting is closely analysed, before being compared with devotional texts dealing with the theme of the spiritual ascent (such as De spiritualibus ascensionibus of Gerard Zerbolt of Zutphen), which Jan Vos knew well. Secondly, this devotional painting is re-placed within its context, namely the Charterhouses of Utrecht and Bruges and Carthusian spirituality in order to demonstrate that together with books, such images played a crucial role in the meditative practices of Carthusian monks.