What does it mean to be "poor in spirit"?

I'm working through a study on "The Beatitudes" of Matthew 5 and would appreciate any insight into Christ's statement: > Blessed are the poor in spirit, for theirs is the kingdom of heaven. > ESV My question is specifically in regard to what "poor in spirit" means, not "kingdom of heaven." An interesting paradigm shift came to me from Dallas Willard's *The Divine Conspiracy*, 1997, which inverts the apparent formulaic assumption of "poor in spirit" to represent a **bad thing.** on pg. 99 of his aforementioned book he puts it this way: > [Willard's paraphrase of Matt. 5:3] "Blessed are the spiritual zeros - > the spiritually bankrupt, deprived and deficient, the spiritual > beggars, those without a wisp of 'religion' - when the kingdom of the > heavens comes upon them." > ... > > ... The poor in spirit are blessed as a result > of the kingdom of God being available to them in their spiritual > poverty. So, seeing "poor in spirit" turned into a bad thing that the kingdom of heaven's availability turns into a good thing was an interesting idea to me, but Williard fails to provide much objective or external support for this beyond his own reasoning. If you're aware of an objective or external argument supporting this perspective, please share it. In short, any answers that can expound on the meaning of "poor in spirit" would be greatly appreciated. Please avoid giving me opinions, and please provide references for all answers, if you can. Thanks!