The 6th principle of Jewish faith says that God communicates with man through prophecy.
The Prophets of Israel were exceptional human beings, called by God to inspire the Jewish people to return to God and His law. In order to be credible preachers, the Prophets had to be role models individuals, possessing an extremely refined character.
Maimonides explains that not every person could become a prophet. There were three key character-traits which were a prerequisite to become a candidate to prophecy and eventually, if God’s so wished, to be called by Him (=prophecy).
An individual who wished to be called by God had to be strong, wealthy and wise.
“Strong” is a person with the ability to control himself, his body, his appetites and the words he or she utters form his mouth. The highest level of strength is achieved when an individual is also able to control his emotions and thoughts. ‘Strength’ is not measured by the ability to control other people, but by the ability to overcome one’s own impulses and appetites.
“Wealthy” is the person who feels that he or she already possesses all the material things he needs. In Judaism, wealth is not measured by quantity but by contentment and appreciation. One person could feel wealthy with 100 dollars, because he does not need more than a 100 dollars, while another person would be considered “poor” even if he has 1 billion, if he needs or wants to have 2 billion dollars. Richness is not measured by what onehas but by what one needs. The correct formula is not: the more you have the richer you are, but the less you need the richer you are.
“Wise”, is not the person who thinks that knows everything, but the one who is constantly growing in his or her thirst to know more. “Jewish Wisdom” focuses particularly in knowing more about God, His wisdom and His will. As our life’s experience become richer, we get to discover new levels of understanding on matters we thought we already knew. The knowledge of God and God’s way is obviously endless. Jewish wisdom is the opposite of intellectual stagnation.
These are the three prerequisites for a person to aspire getting prophecy. Besides being a God fearing Jew, the prophet had to adjust his mind to God’s reality, leaving aside the conventional worldly reality. Being “behaviorally” wealthy, for example, meant that a person had to reach a level of complete lack of interest for material possessions. A mind that expects to receive God’s words could not be distracted with material pursuits.
Paraphrasing rabbi Hayim Pereira-Mendes: “The prophets were prayerful men. It was the habit of this spiritual communication with God, and constant meditation upon His words and ways, combined with right conduct, that qualified the inspired men and women of the Bible to receive Divine inspiration or Divine messages. Just as physical and mental exercise result in greater physical and mental development, and consequently greater physical and mental possibilities, so spiritual exercises result in greater spiritual development, and consequently greater spiritual possibilities.”
According to our tradition there were schools for the training of prophets, like the one established by Shemuel one of the earliest prophets. These apprentices were called bene hanebi-im. In that school they would train to attain behavioral wealth, strength and wisdom and, according to some Geonim, they will also train themselves in meditation techniques, which would mentally prepare them to cope with the overwhelming experience of getting a vision coming directly from HaShem.(If the reader is interested in the fascinating subject of prophecy, I would recommend Rabbi Aryeh Kaplan, z’l, marvelous book Inner Space: Introduction to Kabbalah, Meditation and Prophecy ).
If a person attained such a perfection of character, he will be considered a candidate for Prophet, but he or she would not necessarily receive prophecy. From this point of view ,prophecy could be compared with getting a phone call from God. And having attained perfection of character is like having a cell phone. It enables you to be a potential receiver of God’s phone call. But still, God might or might not call you. That is His prerogative.