Yikes. They're especially poignant/depressing when you consider that those men truly died moments after writing or uttering them. There is very little emotional distance from the end... :-/
My favorite on is by Uesugi Kenshin.
"Even a life-long prosperity is but one cup of sake;
A life of forty-nine years is passed in a dream;
I know not what life is, nor death.
Year in year out-all but a dream.
Both Heaven and Hell are left behind;
I stand in the moonlit dawn,
Free from clouds of attachment."