The study of the iconography of D. Ferdinand’s stained glass collection is absolutely essential to its understanding, since the identification of themes, figures and the way they are treated will allow establishing parallelisms with other works of stained glass of the same period. Such a bridge is indispensable to enchase the aforesaid stained glasses in their historical and artistic context, not only in what concerns the integration of this collection on the vast assets of the Saxe-Coburg and Gotha collection, but also in what concerns a wider framing related to the stained glass typologies of German, Swiss and Dutch production.

The collection gathered by D. Ferdinand II presents pieces of great quality and extremely rich thematic that include scenes of both religious and laic nature.

Among the stained glasses of religious nature are the scenes inspired by the New Testament. The representations of Marian cult are also particularly interesting, including images of the so called Virgin of the Apocalypse of different periods. This allows an analysis of the themes evolution and the establishment of analogies with other examples executed by some of the most famous names of European stained glass, namely the Master of the Amsterdam Cabinet, author of a representation of the Virgin of the Apocalypse – with which one of the images of the Pena collection bears a clear affinity – and Albrecht Durer, who produced several drawings of the Virgin adapted to stained glass, whose iconography displays similarities with another Virgin form the this collection.

Still within the thematic of religious nature, the representations of the saint Church Fathers, iconographic motif commonly found in fifteenth century German stained glasses, are prominent, since the Pena examples enable this collection to fit in an international panorama.

Equally worth of mention are the occasional scenes of the Old Testament (Book of Judith) and of Christian martyrs (Martyrs of Morocco) which confirm once more the immense diversity of themes.

In addition to the religious scenes, the D. Ferdinand collection stands out too for its several stained glasses with subjects of local character, representing patrons and their respective heraldic, as well as episodes related to the history and/or legend of their respective regions (deserving of a special reference is the stained glass with the famous incident of William Tell and the apple), and some gallant scenes (like a young noble playing lute to his Lady).

It can thus be stated that the multiplicity of thematic makes this collection absolutely unique in the national panorama.

Due to the diversity of themes and figurations, the iconographic analysis will have to embrace very different areas, from the heraldic to the study of the garments and drapery, namely concerning the military dress of the knights, which will allow their inclusion in a specific universe of the nobility of the German, Swiss and Dutch territories. In the same way, the analysis of the architectonic framing, including interior representations, will permit the chronologic frame to be set, and establishing analogies with foreign stained glasses possessing similar architectures. The study of the landscape will also try to draw parallels with painting, namely with the Dutch painting that in the seventeen century developed landscape painting. Finally, the iconography of the saints – especially of those of local character - will also play an important role: it will allow the attributes selected to identify them to be compared with the symbols figuring on representations of the saints characteristic of the territories with which they are connected.