espiritu santo

El Serracho raised some interesting religious questions the other day which reminded me of something he and I discussed a few months back: what exactly is the holy spirit?

I saw a bumper sticker the other day that read "3 in 1: Awesome God". Clearly a reference to the trinity. I get the concept of God, that's easy. Jesus as half man, half
God...okay that's a cool story, it has all the mythic elements of a
virgin birth, heroic life, tragic death and ressurection. But the holy spirit? I never quite understood this concept despite my 12 year stint in Catholic school.

Here's what the Catechism says:

691 "Holy Spirit" is the proper name of the one whom we adore and glorify with the Father and the Son. The Church has received this name from the Lord and professes it in the Baptism of her new children.16

692 When he proclaims and promises the coming of the Holy Spirit, Jesus calls him the "Paraclete," literally, "he who is called to one's side," ad-vocatus.18 "Paraclete" is commonly translated by "consoler," and Jesus is the first consoler.19 The Lord also called the Holy Spirit "the Spirit of truth."20

693 Besides the proper name of "Holy Spirit," which is most frequently used in the Acts of the Apostles and in the Epistles, we also find in St. Paul the titles: the Spirit of the promise,21 the Spirit of adoption,22 the Spirit of Christ,23 the Spirit of the Lord,24 and the Spirit of God25 - and, in St. Peter, the Spirit of glory.26

The holy spirit also shows up in the Bible as wind, water, fire, light, a dove and a finger. That doesn't help much. I just can't wrap my head around the trinity concept of God.

Does anyone care to explain the holy spirit to me?