How we cite our quotes: All quotations are from Star Trek VI: The Undiscovered Country.
Quote #1
SPOCK: This will be my final voyage on board this vessel as a member of her crew. Nature abhors a vacuum. I intend you to replace me.
Although The Undiscovered Country primarily views the "future" in a broad, geopolitical way, the theme also resonates within the characters themselves. That's certainly true here: Spock, like the rest of the original crew of Enterprise, is about to be decommissioned, so he's thinking a lot about the ship's—and his own—future.
Quote #2
GORKON: I offer a toast. [raises glass] The undiscovered country. The future.
The phrase "the undiscovered country" is taken from Shakespeare's Hamlet. Although in the text it alludes to life after death, Gorkon uses it as a metaphor for the unknowability of the future.
Quote #3
McCOY: To you, Chancellor Gorkon, one of the architects of our future.
[...]
SCOTT: Perhaps we are looking at something of that future here.
Although the crew of Enterprise is skeptical about the Klingons, they're optimistic about the momentous peace brewing between their people. This dinner is a prelude to that peace, even if it doesn't go exactly as planned.