What does the light motif mean in Tennessee Williams' 'A Streetcar Named Desire''?

Light is generally seen as something that shows up the flaws in something – we use phrases like “holding something up to the light” to mean inspecting the genuineness of something, or talk about “shedding light” on a situation to work out its flaws. One of the main facets of Blanche’s character is her usage of facades, the way she seeks to hide her true self, wrapping it up in layers of deceit, and so it can be seen as natural that she wishes to hide herself from the light in order to avoid exposing her true self to people. The light acts as a visual motif by which Williams conveys metaphorical meanings to the audience. A good example to illustrate this idea would be in scene three when Blanche is talking to Mitch and asks him to put the red lantern over the naked bulb. This is a representation of her shrouding the truth from the light that could show it up – as she says, she cannot stand a naked light-bulb, just as she cannot tell Mitch the straight truth. It is true that Blanche’s obsession with avoiding the light could be seen in a more superficial light as being about her looks – ‘her delicate beauty must avoid a strong light’, Williams tells us. This suggests that Blanche is shying away from the light on account of her appearance, not wanting to diminish her beauty which we know is an important validation device to her, something she clings to in order to reassure herself that she has worth. Yet even here there is metaphor - Blanche's beauty is not skin-deep. For her, her appearance represents the southern belle, the idea and ideal that was her way of life, and reassured her that she was valuable because her class made her superior to others. In the modern era, that way of life has disintegrated. Blanche has thus become ‘delicate’, susceptible to damage in the expository ‘strong light’ of the modern era, represented by artificially bright electric lights. The light motif then links into time, which links back to Blanche's fear of appearing in strong light because of her fear of aging, especially in the effect it has on her looks. Returning to the biographical and emotional level of meaning to the light motif, Blanche’s avoidance of the light could be suggested to stem from the suicide of her husband. In her speech on the subject, Blanche talks about how his coming into her life was ‘like a blinding light’, and how after he killed himself there had never been any light ‘stronger than this kitchen candle.’ Here we see the motif of light in a deeper sense – the light reminds Blanche too painfully of what she lost, of the love she bore so fully for so brief a time, and so she avoids it in order not to have to relive the events as she seems to in this scene. Her real-life avoidance of light is a putting into practice of a metaphorical concept she has in her head to figure the changes in her life. As she tells the story, the lights are all turned off (at her insistence), but stills she seems to vividly relive the events that led to her husband’s death. This might be seen to suggest that her walls are breaking down and her tethering to reality and sanity is wearing increasingly thin.