Mirrors are a key element of the Gothic, symbolising: identity, sense of self, vanity, worldliness, sensuality - or an ethereal, ghostly other-world. For the Lady of Shallott they symbolise her isolation - cursed, she can only see the real world through a mirror which she weaves in a web. A mirror can be a door to an alternate reality.
In some texts, mirrors show us our true selves. In others, it's no more than a pale, cold image - with nothing behind the surface. Mirrors can be magical or literal - showing us things we'd rather not see, like ageing, corruption, desire, lust.
Where vampires are concerned, mirrors test humanity: for a vampire to be seen is to become human.
from 'The Lady of Shallott', Alfred Tennyson, (1842)
And moving thro' a mirror clear
That hangs before her all the year,
Shadows of the world appear.
And sometimes thro' the mirror blue
The knights come riding two and two:
She hath no loyal knight and true,
The Lady of Shalott.
But in her web she still delights
To weave the mirror's magic sights,
"I am half sick of shadows," said
The Lady of Shalott.
She left the web, she left the loom,
She made three paces thro' the room,
She saw the water-lily bloom,
She saw the helmet and the plume,
She look'd down to Camelot.
Out flew the web and floated wide;
The mirror crack'd from side to side;
"The curse is come upon me," cried
The Lady of Shalott.
from Dracula, Bram Stoker, (1897)
I had hung my shaving glass by the window, and was just beginning to shave. Suddenly I felt a hand on my shoulder, and heard the Count's voice saying to me, "Good morning." I started, for it amazed me that I had not seen him, since the reflection of the glass covered the whole room behind me. In starting I had cut myself slightly, but did not notice it at the moment. Having answered the Count's salutation, I turned to the glass again to see how I had been mistaken. This time there could be no error, for the man was close to me, and I could see him over my shoulder. But there was no reflection of him in the mirror! The whole room behind me was displayed, but there was no sign of a man in it, except myself.
"Take care," he said, "take care how you cut yourself. It is more dangerous that you think in this country." Then seizing the shaving glass, he went on, "And this is the wretched thing that has done the mischief. It is a foul bauble of man's vanity. Away with it!" And opening the window with one wrench of his terrible hand, he flung out the glass, which was shattered into a thousand pieces on the stones of the courtyard far below.
from Jekyll and Hyde, Robert Louis Stevenson, (1886)
Next, in the course of their review of the chamber, the searchers came to the cheval-glass, into whose depths they looked with an involuntary horror. But it was so turned as to show them nothing but the rosy glow playing on the roof, the fire sparkling in a hundred repetitions along the glazed front of the presses, and their own pale and fearful countenances stooping to look in.
"This glass has seen some strange things, sir," whispered
"And surely none stranger than itself," echoed the lawyer in
the same tones.
'Mirror', Sylvia Plath, (1961)
I am silver and exact. I have no preconceptions.
What ever you see I swallow immediately
Just as it is, unmisted by love or dislike.
I am not cruel, only truthful---
The eye of a little god, four-cornered.
Most of the time I meditate on the opposite wall.
It is pink, with speckles. I have looked at it so long
I think it is a part of my heart. But it flickers.
Faces and darkness separate us over and over.
Now I am a lake. A woman bends over me,
Searching my reaches for what she really is.
Then she turns to those liars, the candles or the moon.
I see her back, and reflect it faithfully.
She rewards me with tears and an agitation of hands.
I am important to her. She comes and goes.
Each morning it is her face that replaces the darkness.
In me she has drowned a young girl, and in me an old womanRises toward her day after day, like a terrible fish.
from 'The Bloody Chamber'
When I saw him look at me with lust, I dropped my eyes but, in glancing away from him, I caught sight of myself in the mirror. And I saw myself, suddenly, as he saw me, my pale face, the way the muscles in my neck stuck out like thin wire. I saw how much that cruel necklace became me. And, for the first time in my innocent and confined life, I sensed in myself a potentiality for corruption that took my breath away.
from 'Wolf Alice'
In the course of these prowlings, she bumped against that mirror over whose surface the Duke passed like a wind on ice.
First, she tried to nuzzle her reflection; then, nosing it industriously, she soon realized it gave out no smell. She bruised her muzzle on the cold glass... She saw, with irritation, then amusement, how it mimicked every gesture of hers ... She rubbed her head against her reflected face, to show that she felt friendly towards it, and felt a cool, solid, immovable surface between herself and she -- some kind, possibly, of invisible cage? In spite of this barrier, she was lonely enough to ask this creature to try to play with her
The moonlight spilled into the Duke's motionless bedroom from behind a cloud and she saw how pale this wolf, not-wolf who played with her was. The moon and mirrors have this much in common: you cannot see behind them.