From the book Dietrich Bonhoeffer by Dallas Roark, a summation of Bonhoeffer’s views on The Beatitudes:
The poor in spirit are those who have accepted the loss of all things including their own selves for His sake.
Those who mourn are those who do without what the world calls peace and prosperity. Mourning means to refuse to be in harmony with the standards of the world.
The meek are those who give up claims to their own rights for the will of Christ.
Those who hunger and thirst for righteousness are those renouncing all claims to personal achievement, who wait for God’s reign of righteousness.
The merciful, having given up claims to their own dignity, become men for others, helping the needy, sick, outcasts–all those who need any kind of ministry.
The pure in heart become that by giving their hearts completely to the reign of Jesus. Under His rule, He purifies their hearts with His Word.
The peacemakers renounce all violence and maintain fellowship where others would break it off.
The persecuted for righteousness suffer for any just cause, and will be rejected by the world, but God’s kingdom belongs to them. To this motley crew the world says “away with them” and God agrees with the world. But He intends them for the kingdom of heaven, where their reward is great.