One of the great tools of discernment is one that we do not usually like very much: a closed door. The shutting of doors is a gift from God: it is unequivocal direction from God. Even Emerson was able to see that when "the half gods go, the gods arrive" (my possibly inexact quote from memory). Often, we need to know when our particular mission has been accomplished--a shut door can do that. Sometimes, we need a radical change of direction because his thoughts are so far above our schemes and plans--a shut door can do that also.
So next time you face a shut door because someone or some institution or some plan is not cooperating or is not open to what is good, do not take the pagan route of despair or even sadness. But rather, give thanks. Be eucharistic. He has better things in mind for you, even if you do not yet have them in your own mind. The really tragic thing is that too often we fail to see the doors that have just opened because we are so mesmerized by the closed door. In this way, we see again the value of keeping one's eyes on Jesus, as we walk through choppy waters.