The second beatitude (Matthew 5:4): "Blessed are those who mourn, for they shall be comforted." Greek penthountes — the same verb used of weeping over the dead, of ruinous loss, of deep sorrow. In the Septuagint the word appears at Isaiah 61:2, prophesying the Messiah who will "comfort all who mourn" — a verse Jesus applied to Himself at Nazareth (Luke 4:18-21).
The mourning Jesus blesses is not generic sorrow (although God comforts all weepers in their time). Context and scriptural parallels suggest Jesus means primarily mourning over sin — one's own and the world's — and mourning over the state of Zion, the longing for God to finally set things right. Paul tells the Corinthians that godly grief produces repentance (2 Cor 7:10). James commands, "Be wretched and mourn and weep. Let your laughter be turned to mourning and your joy to gloom. Humble yourselves before the Lord, and He will exalt you" (James 4:9-10). Christians do not pretend everything is fine when it is not. We weep at gravesides, at ruined marriages, at injustice, at our own sins, at the world's sickness. And we are blessed in that weeping — because tears before God are not wasted. The comfort is paraklesis, the same root as Paraklētos, the Holy Spirit. Jesus' own tears at Lazarus's tomb (John 11:35) show that mourning is not unbelief. Those who never mourn have not seen clearly.