Blessed are the poor in spirit, for theirs is the Kingdom of Heaven - Matt 5:3
The first of the beatitudes is also the most confounding.
Common sense seems to indicate that the opposite should be true - that the rich in spirit are those who are blessed. This paradoxical statement from Jesus epitomizes the contrarian nature of His teaching. It's not supposed to make sense on the surface. It can only be understood when the entirety of the life of Christ is considered.
There were many great teachers and philosophers in the ancient world. Many of them even taught some of the same things Jesus taught. But none of them taught anything like this.
So why are the poor in spirit blessed? Because they are forced to rely on God to sustain them. The poor in spirit know better than most that we have no inherent life within us. They understand that everything we have - each and every breath we take - comes from God.
They are not easily distracted by the shiny things or petty worries of this world because their souls are too busy thirsting for the Holy Spirit. By completing His mission on the cross Jesus gave us an example to follow. He submitted His will completely to that of His Father. Out of His infinite love for us He endured inconceivable suffering while on Earth so that the veil could be torn and the gates of Heaven could be opened to all who would believe in His name.
While other religions and philosophies aim to teach how to eliminate suffering, Jesus Christ teaches us how to take our suffering and transform it into the eternal glory of God.
Have this mind among yourselves, which is yours in Christ Jesus, who, though he was in the form of God, did not count equality with God a thing to be grasped, but emptied himself, by taking the form of a servant, being born in the likeness of men. And being found in human form, he humbled himself by becoming obedient to the point of death, even death on a cross. - Philippians 2:5-8