Here in Rome, (except in the Vatican) Ascension Thursday is celebrated today, Sunday.
In the same vein as the passage I quoted from Cardinal Newman yesterday, the feast is an ecclesiological as well as a Christological one. From the Catholic point of view it is unfortunate that Christ never called upon a lawyer (he seemed to have a difficult relationship with them) to draft the Articles of Incorporation of the Catholic Church. Instead we are met with the sometimes messy task of justifying Christ's 'founding' of the Church. (How many times do we hear 'Christ Yes, Church No'?) It is sometimes said that Christ proclaimed the Kingdom, but what we got was the Church.
Theologically speaking, it's difficult (and probably unhelpful) to pick one incident from the scriptures and cite it as 'when Jesus founded the church.' Did He do so when he called the twelve? Did the church come into being at the Last Supper when He gave us the gift of the Eucharist? What ecclesial significance do we give to the coming of the Holy Spirit at Pentecost? Historically, what do we make of the first Christians continuing to associate themselves with the synagogues and Jewish customs?
If we are honest, we can't put our finger on a single moment when we can unambiguously say that 'the church was founded by Christ at this time, in this place and for such-and-such a purpose.' Instead, we see that Christ brought the 'visible church' into being in stages, starting with the calling of the twelve and continuing after his Ascension under the guidance of the Holy Spirit. (I say 'visible church' because we can speak of the ecclesia ab Abel.)
The Ascension therefore is important as it marks a new stage in the life of the Church. The Apostles have moved from being the co-workers and companions of Christ in His proclamation of the Kingdom to being His witnesses in Jerusalem and in all Judea and Samaria and to the end of the earth.'
What does this mean in practical terms? A priest of my acquaintance tells of a time he visited the city of Calcutta and was appalled at the poverty and hunger he encountered. He was particularly moved by an emaciated young boy who lay by the side of the road. Unable to eat after seeing this, he brought what he could from his table to this boy who gratefully took the food and vanished into the crowd. Disturbed, the priest fled to the chapel and railed against God - 'Lord, in my ministry, I have preached your love and care for all mankind. How I can I do this after what I am seeing in this city. Why don't you do something to help these wretched people.' A few moments later he received his answer, 'I am doing something to help these people - I sent you, didn't I?'