Naturalistic foliage was a popular decorative detail in the Gothic period, and small animals, birds and people frolic amongst the leaves and flowers. Sometimes the foliage grew into something else: the leaves at Wells Cathedral grow into the head of a man with toothache. English masons specialised in carving heads, which they often positioned so that the head supported something heavy, although the expression on the face rarely seems pleased about this.
Grotesque, semi-human figures like the Lincoln Imp were also very popular and appear not only in the stone carvings but also in wood and around the margins of manuscripts. Such images were requested by the monks and bishops who paid the masons to represent the many temptations of the world, albeit in a charming and humorous way. Other popular images had their origins in a more pagan past. The best known is the Green Man, a Celtic fertility god wreathed in leaves who was adopted by the church as a symbol of life, death and rebirth.
However, most of the carvings depict more traditional religious images such as saints and miracles as related in the Bible. Some of these figures are easy to see, but others are so small and so high up that it is hard to imagine how anyone except the man who made them could ever have noticed them. Perhaps that was the point. Medieval people thought that the cathedral was an earthly representation of the heavenly Jerusalem, and every part of it had to be perfect, even the parts that only God could see.
Source: BBC By: Carol Davidson Cragoe