I'm putting into one place my novena's worth of meditations I wrote on the Pentecost sequence, Veni Sancte Spiritus. Here are the links, in order:
Come, O Father of the Poor
Sweet, Comforting, Refreshing Guest
Labor, Heat and Woe
Fearing the Light of the Holy Spirit
Nothing Without You
Wanting to "Look Good" for God
Why Ask for the Gifts of the Holy Spirit
Give Us Virtue's Sure Reward
In short, what I've gleaned from reflecting on this Sequence is this: The entrance of the Holy Spirit gives light, but that light reveals sin, disorder, attachments, things that need healing and purification, further enlightenment, and an even greater need for the Holy Spirit's work. (Once upon a time I thought it was all about spiritual bling.)
The Holy Spirit's role is to transform us into other Christs. This is not only about inner purification, but also about real fruit born in ministry. But, it is also not only about outward fruit and ministry, but also about inner purification.
I have more to muse on regarding all this, but I'll save it for a future post.