The fragrance of Mary's perfume had filled the house (John 12:1-3).  Emptying half a litre of expensive fragrant oil over Jesus' feet, she was saying 'thank you' for raising her brother from the dead after four days in the tomb (John 11:38-44).  She was pouring out her worship to the Life-Giver.  Jesus said that her act of worship was also prophetic.  It pointed forward to the day when He would be in the tomb and although women would come on the third day after His death with spices to anoint His body, they would find the tomb empty (Luke 24:1-8).  There would be no opportunity to express their personal devotion then: Mary had already done it.
 
Mary's costly act of worship was both a personal response to what Jesus had done, and a divinely inspired prophecy of what Jesus would do.  Although she did not realise it, her action pointed forward to His death and His resurrection day.  That is why Jesus strongly commanded greedy Judas to stop abusing Mary.  Judas wrongly complained that her worship was a waste and there were better things to do with the money, including feeding his own addiction to theft (John 12:4-6).  Despite being chosen to be a disciple, his worship of Jesus was trivial at best.  But Jesus valued Mary's humble self-sacrifice, announcing that it was a signpost pointing forward to His death and resurrection.
 
Every act of true worship says two things to God.  Firstly, it is a response to what God has already done for us (in creation, the cross and daily grace).  Secondly, it announces our hope that we look forward to the day when we will worship Him without any hindrance.  So, for instance, as we participate in Holy Communion we remember the Lord's death (1 Corinthians 11:24-25) and also proclaim the Gospel as we look forward to His Second Coming (1 Corinthians 11:26).

Worship which does not appreciate both the cross behind us, and the crown before us, is a great insult to our Lord.  Trivial worship reveals that our heart is self-centred and not really dependent on all Christ has done.  It has no heavenly perspective - we have forgotten the inheritance to which we have been called.  Therefore today, let us love the Lord with all our mind and soul and strength, giving Him the best, irrespective of the sacrifice, and looking forward to the glories which will be revealed (1 Peter 4:13).