The spirits of prophets are subject to prophets.
A long time ago in Ephesus a prospective believer asked John to teach him to do miracles. The old apostle answered that it was impossible because a disciple doesn't perform miracles: God does.
Part of our salvation 'package' includes a certain measure of spiritual gifting such as wisdom, discernment, and prophecy. Because of it, there are those who automatically assume the position of spiritual advisors or prophets among the flock and become very generous with their word. Today, with the Internet giving us a quick, easy, and cheap way to propagate beliefs and messages, we are inundated with would be prophets of doom creating much anxiety and worry. I'd like to say here that one does not have to be a prophet to know the direction the world is taking. It has been told us a long time ago by real prophets, including Messiah. Even unbelieving honest politicians, economists, historians, and ecologists can see the 'hand-writing on the wall'
When Moses was alive people were trying to supplant him and his prophetic role. The God of Israel knew that it wouldn't get better after his and Joshua's death, so He instituted parameters for prophets. Even if their prophecies were accompanied with 'signs and wonders', they also had to be within the parameters of Torah commandments. Moses teaches that when a prophet performs signs and wonders before you, if his words promote disobedience to Torah, it should be considered a test of our obedience and loyalty to God (Deuteronomy 13; 1-5).
It seems that like today, the believers of the fist century didn't lack would-be prophets so Paul also had to establish parameters to the prophetic gift (1 Corinthians 12 and 14). He suggested that prophecies directed to the 'body' should be 'tested' by the 'body' (1 Corinthians 14:29). I sometime wonder if this attraction towards the prophetic gift is not born of people trying to validate themselves, compensating for their sense of inferiority by making themselves a job for which nobody appointed them. Things would be much different if a 'prophet' would be humble enough (Torah lifestyle is all about humility, not self-promotion) to first submit his 'prophecy' to a mature and level-headed body of elders in his congregation before publishing it for the world on the Internet. Even these daily articles that I write go through the scrupulous and meticulous review of my wife and another editor from our fellowship. Hebrew prophets also were not lone-ranger type of people; they lived in the College and the school of prophets. Many of them came from priestly families and were very knowledgeable in Torah. As far as leaders from the apostolic era, one only has to read the 1 Epistle of Clement, a disciple of Peter, to see a functional knowledge of Torah worthy of a Levitical priest.
May we be wise in using the gifts given to us by the generous Father of all truth and goodness. May we use them for good not evil; to build not destroy; to improve not to confuse; to give life not to kill; to solely glorify Him, not us!