What might Tennyson have meant by the region of shadows and the region of realities in the poem "The Lady of Shallot."

There are many possible answers you might receive to this
question and various critics have debated what the realm of shadows where the Lady of
Shallot lives, and what the realm of reality, into which she momentously enters, might
actually symbolise, with such answers as art and life. However, my own feeling, for what
it is worth, is that this poem is all about the contrast between life and the pale
reflection of life or death in life.

Note the way that the
Lady is shown to live in a world of shadows and greys, which even dominate the "four
grey walls and four grey towers" that make up her abode. She is a character who is
divorced from life, symbolised in the bright colours of the villagers that she watches
go up and down the road. However, life and its spirit is most famously and forcefully
captured in the character of Sir Lancelot, who enters with movement and colour,
described as a "bowshot." His "brazen greaves" are emphasised and adjectives such as
"dazzling" and "sparkled" are applied to him. It is this sight that gives the Lady the
courage to defy the curse and to try and start living, which of course has tragic
consequences. Participation in life is definitely attractive and tempting, but
participating in life will always have its consequences, some of which can be
fatal.