Since the apostles had  walked and talked with Christ before his death and were prepared by him you would think that they would know everything and there would be nothing more for them to discover on their own.  But the more that I read and thought about it I realized that my assumption is not how it should be for them or for us.  He taught them enough and then expected them to rely on the spirit of the Holy Ghost for the rest.  In Acts 10 Peter sees a vision that explains to him that "(vs. 34) Of a truth I perceive that God is no respecter of persons."  Or in other words, the gospel should be taught to all, not just Jews.  The Jews considered non-Jews, or the uncircumcised, to be unclean and not to associated with and not worthy of the word of God.  Concurrently, a centurion named Cornelius fasts and prays and receives an answer to his prayer that he should send servants to Joppa and ask for a man named Simon Peter.  Peter is prompted to join them and return to Cornelius.  Peter teaches Cornelius and those with him and Peter learns in vs. 44 the application of his vision.  He recognizes that the Holy Ghost fell on them and in vs. 45 it is reiterated that the gift of the Holy Ghost was poured out as a gift to the Gentiles.  The Holy Ghost had born witness and chosen them so Peter realizes that baptism is not meant to be withheld from them.  You would think that they would have known this.  And maybe Christ did teach it to them but Peter needed to learn it in the practical sense by the spirit. 

There are many great lesson for all of us here.  Like Peter, won't know all things and we need to follow the whisperings of the spirit to learn them.   But even if we have been taught a lesson, we still need to learn it in the practical sense.  If we are able to follow the promptings and whisperings of the spirit we can be led in all things.  This story is also a great lesson to us not to be the judge of who should receive the word and who shouldn't.  The word is meant for all.  God is no respecter of persons, so neither should we be.  It is also a lesson of times and seasons and accepting the Lord's time table.  The word needed to go to the Jew and then the Gentile.  We don't know exactly why but we know it was the Lord's plan and there is purpose in it.  We, like Peter, need to accept the Lord's time table and trust that there is purpose within.