In describing prophets, Nibley quotes Justin Martyr (also known as just Saint Justin, an early Christian apologist) that "they do not need training speech or skill in controversy and argument but only to keep themselves pure to receive the power of the Spirit of God, so that the divine plectrum can express itself through them as on the string of a lyre, making use of righteous men and revealing to them the knowledge of sacred and heavenly things."
The music analogy there, of the lyre, is what I wanted to make a special point of. Nibley goes on to explain that "holy men can receive God's revelations because they are in tune to the proper wavelength, so to speak. God can play on them as a plectrum plucks the strings of a lyre because they are prepared to vibrate to his touch -- not by virtue of any special training, and not whenever they choose to respond, but whenever it pleases God 'from time to time' to move them from heaven."
Now of course, this analogy can apply to us. We must be in tune to the spirit and prepared to respond to the touch of God in order to receive the personal revelation that he has for us. That is how he works with us to accomplish his will, for example:
1 Nephi 18:1And it came to pass that they did worship the Lord, and did go forth with me; and we did work timbers of curious workmanship. And the Lord did show me from time to time after what manner I should work the timbers of the ship.And, like Nephi, from time to time the Lord will enlighten our understanding and inspire us to action "precept upon precept; line upon line; here a little, and there a little" (Isaiah 28:10). This individual and intimate communication with our Heavenly Father is critical for our spiritual development, but is not the same as the revelation that comes to a prophet.
As touched upon in my first two paragraphs, a prophet is not someone trained to speak or skilled in his ability to argue. Unlike philosophers and scholars who seek to understand by their own minds and argue by their own skill "it was not their [the prophets] wont to build up a case by formal argument, but simply to report the truth as reliable witnesses, without any disputation at all" as it is only by "revelation from outside" that man can "be freed from his fearful confinement within the narrow cell of his own limited experience" (Nibley but this bit is from Ch 2).
After all, the wisdom/understanding/abilities of any man are nothing in comparison with God, and for all our efforts, quite often completely miss the mark. God himself said "For as the heavens are higher than the earth, so are my ways higher than your ways, and my thoughts than your thoughts" (Isaiah 55:9) so how can we ever hope to know the mind of God unless He gives it unto us? We can only know through partially through personal revelation (as just discussed) AND through faith in the revelation received by the prophets.
Without the gift of prophets -- "of direct revelation from heaven such as is received only by prophets" we "would be no better than the heathen -- well-meaning but bankrupt" (Nibley). Seeking to do the will of God yet without the power to access the fullness of His will, and thereby worshipping him "in vain" and (be in purposefully or unconsciously) resorting to "teaching for doctrines the commandments of men" (Matthew 15:9, Mark 7:7).
Paul taught of the purpose and importance of the witness of prophets and apostles over and over again in Ephesians. He explained that they were given "For the perfecting of the saints, for the work of the ministry, for the edifying of the body of Christ: Till we all come in the unity of the faith, and of the knowledge of the Son of God, unto a perfect man, unto the measure of the stature of the fulness of Christ" (Ephesians 4:11-13). There is an edification, unification, and perfection of the Saints that can only be perpetuated through a prophet -- and this is because the body of the saints is "built upon the foundation of the apostles and prophets, Jesus Christ himself being the chief corner stone" (Ephesians 2:20) and there are revelations made known only prophets that we may hear from them and through our faith understand:
Ephesians 3The Jews had difficulty accepting this, as do many today. "God had visited the earth in remote times; he had spoken to Abraham and to Moses. Venerable traditions burdened with a magnificent weight of art, poetry, scholarship, and ritual attested the sincere devotion of the race to the memory of God's visits to men in times past. But to ask men to believe that that same God had spoken in their own day, and to a plain man who walked their streets—that was simply too much to take! That was the test that Christ's generation could not pass.
3 How that by revelation he made known unto me the mystery; (as I wrote afore in few words, 4 Whereby, when ye read, ye may understand my knowledge in the mystery of Christ) 5 Which in other ages was not made known unto the sons of men, as it is now revealed unto his holy apostles and prophets by the Spirit;
It was a test that few have ever passed: the humiliating test of recognizing a true prophet and taking instruction from the weak and humble things of the earth" (Nibley).
I add my witness that our age has NOT been "excused from taking the same test of authority" and that God HAS called prophets and they do speak to us words from heaven that we would do well to listen and obey (Nibley). It may be "unwelcome news to the world" that "the true church must and will always have living prophets" (Nibley) but it is nonetheless the case -- and I for one am grateful for divine precepts and direction that come from God through his appointed spokesmen, and address the needs of the saints in this day, in our complicated and increasingly wicked world.