Heroes and....antiheroes

Raffaello Sanzio, "Saint Michael tramples Satan"

Louvre, Paris (1518)

Light and dark may be used as metaphors. Heroes and heroines dress in light colors, bad figures are related to dark elements.

Allegory of the Cave

In the seventh book from "The republic" (514 b - 520 a), Plato illustrates "our nature in its education and want of education", trought the Allegory of the Cave. This relates to the idea of forms as people struggle to see the reality beyond illusion.

After "returning from divine contemplations to human evils", a man "is graceless and looks quite ridiculous when – with his sight still dim and before he has gotten sufficiently accustomed to the surrounding darkness – he is compelled in courtrooms or elsewhere to contend about the shadows of justice or the representations of which they are the shadows, and to dispute about the way these things are understood by men who have never seen justice itself?" (517d-e)

"The night is long which never finds the day"

John Singer Sargent, "Ellen Terry in the role of Lady Macbeth" (detail), 1889Tate, London

Metaphors of light and darkness are used in Macbeth by William Shakespeare to illustrate important themes such as evil and dishonest gain.

For example, Shakespeare uses the metaphor of darkness to illustrate Macbeth's slide towards depravity. He cannot face his deeds but needs the dark to hide what he is doing:

  Stars, hide your fires

  Let not light see my black and deep desires

  (i.iv.50-51)

The 'Force' and the dark side

In the epic space opera 'Star wars' (first movie in 1977) light and dark symbolize the contrast between good and evil. 

One of the prominent elements of Star Wars is the 'Force', an omnipresent energy that can be harnessed by those with that ability. It is described in the first produced film as 'an energy field created by all living things [that] surrounds us, penetrates us, [and] binds the galaxy together'.

The Force allows users to perform a variety of supernatural feats (such astelekinesis, clairvoyance, precognition, and mind control) and also can amplify certain physical traits, such as speed and reflexes; these abilities vary between characters and can be improved through training.

While the Force can be used for good, it has a dark side that, when pursued, imbues users with hatred, aggression, and malevolence.

Get rid of your bad dreams

Photographers and artists are always looking at light as the key element in any composition, which is certainly extremely important for dark advertisements.

Dark ads are usually used to portray a scary situation, or a serious issue, creating a dramatic impact. Light represents a way to overcome problems and solves negative situations.

Don't curse the darkness: light a candle

In many chinese proverbs, you can find light as...

...a way to overcome problems:

- Better to light one small candle than to curse the darkness (Confucius)

- You can only enter half way into the dark forest before you begin to come out the other side

...a time measurement of everyday life:

When the sun rises, I go to work.

When the sun goes down, I take my rest. 

I dig the well from which I drink. 
I farm the soil which yields my food. 
I share creation. 
Kings can do no more.

...a representation of goodness and beauty:

If there is light in the soul,
there will be beauty in the person.
If there is beauty in the person,
there will be harmony in the house.
If there is harmony in the house,
there will be order in the nation.
If there is order in the nation,
there will be peace in the world.

Other ways to say...

Light:

http://www.synonym.com/synonyms/light/

Dark:

http://www.synonym.com/synonyms/dark/