I am sure this is a rather easy question to answer, so you probably will like it. =) I just thought that white was considered the Holy color, you know pure and stuff since that is what brides wear.
Perhaps the somber colours they are showing their renunciation of the world and lack of vanity?
hmm…well I like that answer. =)
They don’t. Well, they don’t anymore, and they never all did. It depended on the order: some orders wore navy blue, or light blue, or white. Some wore the full habits, some wore outfits that looked like business suits with just the headgear. Nowadays many nuns just wear simple modest street clothes without the headgear - but again it depends on their order.
“The analyst went barking up the wrong tree, of course. I never should have mentioned unicorns to a Freudian.” – Dottie (“Jumpers” by Tom Stoppard)
As for why nuns USED to wear black, that’s easy, too. Most habits were designed at the time the order was founded, and were simply variations on the type of dress common at that time. If you look back at very old photographs, you’ll see that ordinary people commonly wore black – brighter colors were more expensive and generally worn only by the upper class.
My guess:
In the beginning, the habits weren’t necessarily black, they were just dark. Dark cloth hides stains and wear better than lighter colors. It is also cheaper to dye, since you could just use a mixture of whatever dyestuff was available (rather than needing a lot of a specific color).
Most orders were founded on the idea of simplicity, hard work, and service. Wearing colors that are hard to make and maintain took away from that.
“If you prick me, do I not…leak?” --Lt. Commander Data
Addendum to my guess:
Most orders were founded in the Middle Ages, and needed to make and dye the cloth for their habits themselves.
Just in case that wasn’t clear…
“If you prick me, do I not…leak?” --Lt. Commander Data
a couple points:
in old pictures, the medium is Black and White. you wore scarlet, it showed as black. Dark blue? ditto. dark green?
…see a trend? black and white photos are an unreliable basis for making assumptions regarding anything except the clothing styles.
also, white only became the color associated with brides (and bridal gowns) around the Victorian times, with the rise in personal levels of wealth and having the disposable income to spend on a “one-wear” garment. before then, the bride generally wore her “best dress”, of whatever color (or regional costume style).
next one who says “Fates a bitch” gets whacked with my measuring stick.
What column does this refer to?
Moving this one to GQ.
Jill
Perhaps it’s just a habit.
Tris
Imagine my signature begins five spaces to the right of center.
IIRC in the middle ages and renaissance, black dye was expensive and considered ostentatious.
Because they wuz woman folk. They wanted to make sure that they were looked upon as chaperones of spriritual guidance as opposed to babes wearing a sheet. There was a need to de-emphasize the shapely curves & pouting breats by throwing a dark shroud over her. Look at a relief map sometime- colors are used as a tool to help make mountains stand out.
Almost as good as “Neither a burrower nor a lander be.”
Groan scale: 8.8
Have any issues, Opus? 
“Pouting Nun Breasts” might be a neat band name, though.
Next question…how do breasts pout?
I assure you, no issues here- I just felt that was better than “champagne glass-sized orbs of dancing loveliness”.
Many people have the mistaken assumption that the subjects of old paintings or photographs were wearing black because they were sombre. In fact, black clothing was regarded as finery because it faded easily. The pilgrims for example wore clothes that were dyed blue, green, red, or yellow for their everyday wear and saved their black clothing for a special occasion like having a portrait painted.
Paula nailed it early on, folks. The color signifies the order. Benedictine monks wore black, but others wore brown or white or gray. There are place names in London such as Greyfriars and Blackfriars that point out the difference.
From the Asleep at the Wheel CD, Bob Wills Rides Again:
“It must be hard to lose your wife.”
“Sometimes it’s damn near impossible!”
It saddens me to see so many people wrong. They wear black because black can also mean the negation of worldly vanity and ostentation. That’s why conservative political parties and nuns and priests where black. It’s also the promise of the future resurrection. You don’t believe me? That’s ok, I wouldn’t believe me either. Check it out in any symbolism dictionary.
I was told a long time ago (incorrectly, apparently) that nuns wore black as a symbol for the mourning of the death of Jesus.