There's a certain Slant of light Theme of Isolation

That light in those winter afternoons isn't uplifting like the light of summer. Nope. No sunscreen needed here. Rather, it's isolating in "There's a certain Slant of light." The speaker has her feelings put on the spot because of that light, making everything around her seem oppressive like that "imperial affliction."

1. How does the imagery of that slant of light illuminate the speaker's feeling of isolation? What does it reveal to her?
2. Is there any difference between isolation and sadness in the poem? Why or why not?
3. How do those "Cathedral Tunes" contribute to the speaker's isolation? What's the connection between those tunes and the speaker's oppression?
4. Do those dashes contribute to the poem's theme of isolation? Would the speaker have appeared any less isolated without them?

They may seem like close cousins, but isolation and sadness are two different things in Dickinson's poem. Isolation indicates the speaker's "internal difference."

Not so fast there. Isolation leads to sadness, so the two are inseparable in Dickinson's poem and help to create the speaker's feeling of an "imperial affliction."