For to me to live is Christ, and to die is gain. (Philippians 1:21, ESV)The Greek that is used here could more literally be translated, "To Live: Christ! To Die: Gain!"
The meaning here is clear: For Paul to live, well, that will be like sharing in the very person of Jesus Christ. To live is to suffer for the sake of the Gospel. To live is to be persecuted. To live is to potentially remain in prison to eventually be executed. To die... now that is gain. To die is to be removed from all of this. As I have heard before, Paul must've thought, when conversations of execution came up, "You can't threaten me with heaven..."
When Paul, under the inspiration of the Spirit, penned* these words, I wonder if he knew how much comfort they would bring to those who are suffering for Christ and those who are close to death?
*(Paul usually didn't write these letters himself. So, I say "penned" knowing that he most likely had someone there doing the actual writing while he speak these words.)