Answers the Ralbag, Rabbi Levi ben Gershom: she was certain, because in fact every single one of the prophets' disciples was a G-d-fearing individual.

Let us examine this idea.

In a number of places in Scriptures, we find that each of the great prophets had a group of students studying under him, learning to attain prophecy. What did their discipline consist of?

For one thing, they would meditate upon the greatness of Hashem, to try to become close to Him and experience His presence. (See Maimonidies, Yesode Hatorah 7:1.) But hand in hand with that, the aspiring prophet would work upon his own character traits and his own spiritual identity, endeavoring to perfect himself to the point where he would become a worthy receptacle for the Divine spirit. In a passage in the Talmud (Avoda Zara 20b), Rabbi Pinchas ben Yair outlines the step-by-step system in aspiring to self-perfection that one must climb, bit by bit, until he may be worthy of the Divine spirit (Ruach Hakodesh).

Rabbi Moshe Chaim Luzzato, the great eighteenth-century scholar, wrote an entire work, Mesillas Yesharim (Path of the Upright), in which he elaborates in detail on each of the steps in Rabbi Pinchas ben Yair's system. This volume has become a classic in the sturdy of ethics, perused by countless people who strive to better themselves.

Prophecy was not, Heaven forbid, an occult science. Rather, each and every one of the prophets' discriples was a living Messilas Yesharim--and it was this that prepared him for the prophetic experience!