Pentecost: Outpouring of the Holy Spirit.
And why HOLY Spirit? For three reasons, mainly.
First, because there are certain creatures in this universe who are, and always will be, and never shall be anything other than, spirits. And yet they are not in the least holy. Or rather, more precisely, they have ceased to be holy - mostly because they think they have found something better than Divine holiness. (And of course there's always something better than what one has been Divinely given - until one finds that the "better" is actually an outcome far worse than one could ever have bumped into round the corner of one's most nightmare-haunted despairs.)
Second, because there are other kinds of creatures in this universe, who are not and will never be spirits, and yet - such is the Divine humility - who can be made holy. And indeed must, if they are ever to find wholeness (which process can be made immeasurably easier by one simple procedure: namely, by firmly shutting one's ears to the entreaties of the first-mentioned sort of creature).
Lastly, because everywhere in the universe there is a ravenous need, across every category of creature however high or low, for One who (a) has all the power that inheres in being spirit and not flesh, (b) stores holiness in unasked-for abundance, and (c) actually shares and even sheds this same holiness to all who ask for it (as opposed to our human custom of hoarding and rationing it). This One also has a very curious kinship with human beings in that, while He is wholly unlike the convoluted mess we've succeeded in making ourselves, He is also like us enough to be the slaking of our every human thirst, and the satisfying of our every human desire.
Upon discovering which, our most common initial response, at this point in the Journey, is to bid the chauffeur a hasty "Drive on!" We humans long ago became much too mature, too ironic, and (ironically enough) too heroically self-determining, ever to be resigned to any merely happy ending to our story. And yet not only is this incorrigibly happy Door still open, but lo, One - upon whom depends the salvation of the entire universe - has already passed through it.