Towards the end of the Middle Ages two factors dominate religious life: the extreme saturation of the religious atmosphere, and a marked tendency of thought to embody itself in images……
The spirit of the Middle Ages, still plastic and naive, longs to give concrete shape to every conception. Every thought seeks expression in an image, but in this image it solidifies and becomes rigid. By this tendency to embodiment in visible forms all holy concepts are constantly exposed to the danger of hardening into mere externalism. For in assuming a definite figurative shape thought loses its ethereal and vague qualities, and pious feeling is apt to resolve itself in the image.
J. Huizinga, The Waning of The Middle Ages