The Power of Sunlight in Medieval Churches

By Alice Isabella Sullivan

Medieval churches have harnessed the power of sunlight to define and accentuate sacred spaces, as well as indicate holiness. This is evident across Europe and the Mediterranean, as well as in the regions that developed at the crossroads of traditions and worldviews, as is the case in Eastern Europe.

In the Christian tradition, the carefully observed movement of the sun across the sky has informed the orientation, design, as well as the distinct architectural and decorative features of churches throughout the Middle Ages. Recent studies have demonstrated that light effects served as a unifying feature of religious spaces, bringing together the architecture, decorations, and ritual performances unfolding within the buildings.


For example, scholars have observed that the general East-West orientation of Christian churches was established so that the rising sun first illuminates the altar. This helped draw the connection between natural light as a manifestation of divinity and in particular Christ, in view of John 8:12 “I am the light of the world: he that follows me, walks not in darkness, but shall have the light of life.” But whereas these daily theophanies reinforced the associations of natural light and holiness, especially during the celebrations of morning liturgies, additional light phenomena evident throughout the year were deployed with precision to underscore other theological statements.

Church of the Holy Cross, exterior view from southwest, built 1487, Pătrăuţi, Moldavia, modern Romania – photo: Alice Isabella Sullivan

The church of the Holy Cross at Pătrăuți Monastery in Romania offers an intriguing case study where several natural light phenomena have been observed and documented. Begun in 1487 on the day of the summer solstice (according to the extent dedicatory inscription on the west façade, set above the main entrance), the church is one of the earliest ecclesiastical foundations commissioned by Prince John Stephen III of Moldavia (r. 1457-1504). For more than 15 years, Father Gabriel-Dinu Herea (the former local priest) recorded and interpreted several remarkable light effects inside the church at Pătrăuți. From his observations, it became clear that the sun’s path during the fixed dates of the equinoxes and solstices proved to be particularly relevant for the construction and decoration of the edifice. Here are a few key examples.

Sunlight entering the church through the west entryway and aligning with the altar, church of the Holy Cross, built 1487, Pătrăuţi, Moldavia, modern Romania – photo: Gabriel-Dinu Herea

A “light path” forms along the axis of the church for about two weeks around the spring and summer equinoxes, that is March/April and September, respectively. Each afternoon, between about 5:40 and 6:00, the sunlight aligns directly with the narrow doorways at the thresholds and illuminates the altar. This alignment would have corresponded with the celebrations of Vespers, which centered on Christ’s coming as Light into the darkness of the world.

Sunlight illuminating the image of St. Zosima and St. Mary of Egypt painted above the main entrance during the winter solstice, church of the Holy Cross, built 1487, Pătrăuți, Moldavia, modern Romania – photo by Gabriel-Dinu Herea

Around the solstices, additional light effects are evident at Pătrăuți. During the winter solstice, for example, which in 1487 took place on December 13, a sunray entering through the south window of the naos illuminates the image of St. Auxentius situated inside the niche on the north wall, near the sanctuary. This occurs around 1:00 pm on the feast day of the saint. This suggests that perhaps a special celebration in honor of this saint took place on this day after the liturgy. In this same period, the first morning sunrays entering through the south window of the pronaos, fall directly on the image of St. Zosima and St. Mary of Egypt painted above the main entrance to the church. The light illuminates the chalice with the Eucharistic Christ in between the two holy figures, thus underscoring once again the image of Christ as the “Light of the world.”

John Stephen III and His Family, lit by the sunlight from the altar window, interior votive mural, south wall of naos, church of the Holy Cross, built 1487, Pătrăuţi, Moldavia, modern Romania – photo: Gabriel-Dinu Herea

But perhaps the most complex light phenomenon observed at Pătrăuți is the one that occurs around the summer solstice. It connects different sections of the building and portions of the mural decoration, emphasizing their theological import and the devotional concerns of the patron. For about thirty days around the summer solstice—a period that also corresponds with the Feast Day of Saint John the Baptist on June 24—an important light effect unfolds inside the church. The morning sunlight enters through the altar window and lands on the votive portrait of the patron, John Stephen III, located on the south wall of the naos. As the sun moves across the sky, the ray descends from the wall to the floor of the church. It then begins an almost three-hour-long journey from the votive painting to the altar.

Click here to watch a video of this event

Since Stephen also had the name John, the light effect on the feast of Saint John the Baptist, and its journey from the votive mural to the altar, associated the patron with the saint and metaphorically brought him to life. As such, sunlight indicated the Moldavian prince’s symbolic descent from the wall of the church and subsequent journey to pay reverence to the altar (i.e., Christ). The slight deviation of the positioning of the altar window indicates that this light effect was intentional and carefully planned from the outset in dialog with the votive painting of the patron designed for the opposite south wall of the naos.


As such, the church at Pătrăuţi stands out for its distinct choreography of moving sunlight, which demonstrates the precise planning and decoration of the edifice relative to the movement of the sun across the sky. The recent article, “Space, Image, Light: Toward an Understanding of Moldavian Architecture in the Fifteenth Century,” by Gabriel-Dinu Herea, Vladimir Ivanovici, and myself, which appeared in Gesta 60, no. 1 (2021), details several of the key light phenomena at Pătrăuți, demonstrating how sunlight was deployed to unite aspects of the architecture, decoration, and ritual at this site.

From the case of Pătrăuţi, it becomes clear that it is important to examine simultaneously the various facets of religious spaces and their more ephemeral dimensions. The material evidence in the form of architecture, mural decoration, and liturgical objects should be studied in conjunction with the performance of rituals, music, light effects, and olfactory aspects. Such approaches could help enhance our understanding of the varied meanings and functions of religious spaces. The careful study of the buildings themselves, precise measurements, and meticulous simulations can recreate the multitude of sensorially-rich phenomena that unfolded in religious buildings. From these, natural light emerges as a unifying factor of the structuring of sacred spaces.

The complex principles used to deploy natural light in the historically significant church at Pătrăuți invite further analyses along similar lines of inquiry for other medieval churches from across the Byzantine and Slavic cultural spheres.


Alice Isabella Sullivan is an art historian specializing in the medieval history, art, and culture of Eastern Europe and the Byzantine-Slavic cultural spheres. She has authored award-winning publications, is co-editor of Byzantium in Eastern European Visual Culture in the Late Middle Ages, and co-founder of North of Byzantium and Mapping Eastern Europe. Follow her on Twitter @AliceISullivan

Further Reading:

G.-D. Herea, The Symbolic Presence of the Sun at Pătrăuți (Timișoara: Editura Universităţii de Vest, 2020), translated from Romanian by A. I. Sullivan, with a foreword by M. E. Frîncu, and an introduction by V. Ivanovici.

A. I. Sullivan, G.-D. Herea, and V. Ivanovici, “Space, Image, Light: Toward an Understanding of Moldavian Architecture in the Fifteenth Century,” Gesta 60, no. 1 (2021): 81–100.

Click here to read more from Alice Isabella Sullivan

Sunlight on the face of Adam in the Descent into Hell, interior mural, north wall of naos, church of the Holy Cross, built 1487, Pătrăuţi, Moldavia, modern Romania – photo: Gabriel-Dinu Herea




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