Hair is very important in symbolism. You will notice, to begin with, that all almost all saints have it. There is a debate between Thomist and followers of Augustine as to whether there is actually hair in heaven. I prefer to think that there is and some day we will be reunited.
Loose flowing hair is often the sign of penitence. Think of the woman who wept on Jesus’ feet and then dried them with her hair. According to George Ferguson’s book, “Signs and Symbols in Christian Art,” this is why monks often grow their hair long – a sign of penance.
In much traditional clothing from years gone by young single women would let their hair hang long and free while married women hid their hair under scarves or fancy hats. In a similar fashion many virgin saints are depicted with the same long flowing hair. Hair that is flowing and distressed, hanging over the face is a sign of great sorrow or distress.
Grey hair may be a sing of age, but it is also a symbol of wisdom. A beard is also a symbol of wisdom which is why a “lack beard” was considered someone not to be taken too seriously or at least who is young. It is interesting however that at times diocesan clergy were discouraged from having facial hair though certain orders made it a rather important tradition.
To pull at one’s hair is a symbol of great distress. To have one’s hair pulled or beard plucked is a sign of the greatest disrespect.
The way hair is cut may be very important. To have a shaved head might be a sign of a vow. A tonsure, the shaving of the head at the crown, is also a sign that a vow has been taken which is why you will see monks with that peculiar “forced” male balding pattern on their head.
A radical change in hair can mean a radical change in life. Wild hair is the symbol of evil intent or an unkempt mind. If a devil is depicted with hair it is usually in some sort of exaggerated state. It may be luscious, fully, and somewhat wild, or show evidence of a severe retreat (and be somewhat greasy) or he might be bald altogether – not because of a vow, but because his lifestyle caused it.