Hildegard was a 12th century Christian mystic. This image comes from one of her illuminations. In this picture she recorded an experience in which she was inflamed by a fiery light, and which inspired her to write, draw, and compose music.
I've enjoyed listening to A feather on the breath of God a recording of her compositions by Gothic Voices. You can listen to a sample.
Many of her illuminations have circular imagery, and the one from which the image below comes is a mandala. Many of Hildegard's illuminations (including the complete illuminations which the two images found here reproduce only in part) can be found in Illuminations of Hildegard of Bingen.
Illuminations includes translated excerpts of Hildegard's writing and commentary by Matthew Fox.
Hildegard coined the term viriditas which can be translated as "greening power." She sees viriditas in divinity as a power which enlivens, encourages creativity and fruitfulness. She wrote, The word is all verdant greening, all creativity. And when she listens for the voice of divinty she hears:
I am the breeze that nurtures all
things green.
I encourage blossoms to flourish with ripening fruits.
I
am the rain coming from the dew that causes the grasses to laugh
with the joy of life.
Illuminations of Hildegard of Bingen is published by Inner Traditions