Now when he saw the crowds, he went up on a mountainside and sat down. His disciples came to him, and he began to teach them saying: "Blessed are the poor in spirit, for theirs is the kingdom of heaven. (Matthew 5:1-3)

Jesus has now chosen Peter, Andrew, James, John and other disciples and "his fame spread throughout all Syria." (Matthew 4:24) We do not know how long he had been teaching and healing before he went up on this mountainside.

Jesus begins his sermon on the mount by congratulating - even proclaiming happy - those who are ptokhos pneuma. This is not just being without. The Greek ptokhos is to be destitute and entirely dependent on others, reduced to begging.

In other gospels ptokhos will be the object of the sentence, here it is an adjective. Poor in spirit, or mind, or in living. Pneuma is the breath, wind, source of being.

The Greek tense is present indicative. The nuance of Greek tenses is beyond my expertise. But there is clearly a sense of the action being finished. Those who are spiritually destitute and/or dependent are - already - in possession of the kingdom of heaven.

It is possible - but unusual - to translate this as, "Happy are the poor in spirit they are the kingdom of heaven."

Above is an image of heaven by Hildegard of Bingen.