There is an old jewish saying that there is no stirring above until there is a stirring below. God remains unknown until we put forth the effort to receive a revelation. In the language of the Mormon church we say that you receive no witness until after a trial of your faith. If we wish to know if God is there, or if a point of doctrine is true, we must pray.
D&C 32:8-9
8 And now, my beloved brethren, I perceive that ye ponder still in your hearts; and it grieveth me that I must speak concerning this thing. For if ye would hearken unto the Spirit which teacheth a man to pray ye would know that ye must pray; for the evil spirit teacheth not a man to pray, but teacheth him that he must not pray.
9 But behold, I say unto you that ye must pray always, and not faint; that ye must not perform any thing unto the Lord save in the first place ye shall pray unto the Father in the name of Christ, that he will consecrate thy performance unto thee, that thy performance may be for the welfare of thy soul.
You can only know God through prayer and revelation. God asks that we pray so that we can begin to grow our spiritual muscles and understand that we must desire righteousness and stretch ourselves through faith.
The question now is, how do we distinguish between revelation and emotion, or personal desires.
One way to discern is to apply to a revelation the "what is its purpose test", or "purity of purpose test". The question often arises among missionaries that while in the field they met many others who had some sort of spiritual experience, and that they think that becasue they were sincere, that matbe they did have a spiritual experience and maybe they're alright.
Lets discern the spirit of this. Whats the purpose of the revelation? If someone is going to say that they received a revelation that tells them that they do not need to be baptised for the remission of their sins, that they are not in need of the companionship of the gift of the Holy Ghost, that they have no need to hear a prophets voice, that surely they don't need to be sealed to their spouse for time and all eternity or any other of the blessing that come from fellowship in the kingdom of God, be suspicious. The Holy Ghost does not give that kind of a revelation.
The Holy Ghost does not go around contradicting himself. If someone says to me that they received a revelation that Jesus was not the Christ, I would be suspicious. I don't find that all that difficult to discern.
What is its purpose. If the revelation genuinely comes from the Lord, its purpose is not going to be to tell someone to close their minds, but to instead open themselves up and receive further light and knowledge. Revelations are not easy things either. They tend to be demanding, they ask a person to stretch and grow.
A good way to study revelations is to look at past revelations and study them to identify characteristics. Two words that are in nearly every scriptural example where revelation is given are
Joy and
Peace.
Characteristic
Joy. The gospel is called the "glad tidings of joy" (D&C 128:19). It caries the spirit that enlightens the heart and brings joy to the soul.
Isa. 35: 10
10 And the ransomed of the LORD shall return, and come to Zion with songs and everlasting joy upon their heads: they shall obtain joy and gladness, and sorrow and sighing shall flee away.
"I was filled with unspeakable Joy" Joseph Smith said as he described the feeling he experienced in the First Vision "My soul was filled with love and for many days I could rejoice with great joy and the Lord was with me."
The three words most common to the spiritual descriptions of those embracing the truths of salvation are: Joy, gladness and rejoicing. As Paul said the gospel is the "Oil of gladness" (Heb 1:9)
Characteristic
Peace, a companion of Joy. A feeling frequently found when describing the Spirit of the gospel or ther presence of the Holy Ghost.
Having promised his diciples the companionship of the Holy Ghost Christ said "Peace I leave with you, my peace I give unto you: not as the world giveth, give I unto you. Let not your heart be troubled, neither let it be afraid" (John 14:27)
By contrast, the spirit of the devil; what does it produce? Confusion, disorder, misery. The spirit of God produces calmness, order, happiness.
The First Vision is a great example. It brought a state of calmness and peace indescribable.
George A. Smith said:
When a mans mind is illuminated by a dream it leaves a vivid and a pleasant impression. When it may be guided by the Spirit of God it leaves the mind happy and comforted and the understanding clear.

Oliver Cowdery in describing the restoration of the Aaronic priesthood at the hands of John the Baptist said:
Earth has not the power to give the joy or bestow the peace or comprehend the wisdom which was contained in each sentance as they were delivered by the power of the Holy Spirit.
Similarly in the Old Testament Gideon named the place where he stood face to face with the angel of the Lord Jehovah-shalom meaning "The peace of the Lord". (Judg. 6: 24)
Mosiah 4: 3, 20
3 And it came to pass that after they had spoken these words the Spirit of the Lord came upon them, and they were filled with joy, having received a remission of their sins, and having peace of conscience, because of the exceeding faith which they had in Jesus Christ who should come, according to the words which king Benjamin had spoken unto them.
D&C 6: 23
23 Did I not speak peace to your mind concerning the matter? What greater witness can you have than from God?
After his death, Joseph Smith appeared to Brigham Young in a dream and instrructed him to ""Tell the people to be humble and faithful, and be sure to keep the Spirit of the Lord, and it will lead them right. Be careful and not turn away the small still voice; it will teach you how to do and where to go; it will yield the fruits of the kingdom. Tell the brethren to keep their hearts open to conviction, so that when the Holy Ghost comes to them, their hearts will be ready to receive it. They can tell the Spirit of the Lord from all other spirits; it will whisper peace and joy to their souls; it will take malice, hatred, strife, and all evil from their hearts; and their whole desire will be to do good, bring forth righteousness and build up the kingdom of God. Tell the brethren if they will follow the Spirit of the Lord they will go right. Be sure to tell the people to keep the Spirit of the Lord; and if they will, they will find themselves just as they were organized by our Father in Heaven before they came into the world. Tell the people to be sure to keep the Spirit of the Lord and follow it, and it will lead them just right."
Brigham Young, vision, Feb. 17, 1847, in Brigham Young Office Files, 1832–1878, Archives of The Church of Jesus Christ of Latter-day Saints, Salt Lake City, Utah; spelling, punctuation, and capitalization modernized.
Characteristic
Enlightenment
To receive revelation is to receive light. As all revelation edifies, so all revelation enlightens.
D&C 50:23
And that which doth not edify is not of God, and is darkness.
that's a good spiritual test. Does it edify?
The word edify comes from the word edifice. An edifice is viwed properly to be a chapel, or a temple. When a chapel or temple was ina state of reconstruction or improvement we called it edifying it. That which edifies improves, build up.
To edify causes you to be built up, added to, improved.
Edify has a companion and that is "To enlighten". The revelations tell us that truth shines, it enlightens both the heart and mind. It quickens the understanding. Or as Joseph Smith said "The sudden stroke of ideas." That quickening of understanding, or feeling of pure intelligence flowing through you, that's not just a matter of a ligth coming on where it used to be dark. Its more a case of a light that was already burning burning more brightly, so that we can see further.
Characteristic
Pure, virtuous
D&C 67: 9
9 For ye know that there is no unrighteousness in them, and that which is righteous cometh down from above, from the Father of lights
James 3:17
But the wisdom that is from above is first pure, then peaceable, gentle, and easy to be intreated, full of mercy and good fruits, without partiality, and without hypocrisy.
Revelation shows the attributes of God. A manifestation of the nature and character of God. Will a revelation lack wisdom? God is not unwise. Will it lack virtue, purity, or any other Godly attribute? The revelations of heaven will likewise not lack these attributes. The Holy Ghost effects the heart and soul of a man not only createing an abhorence for sin but also gives birth to a disposition to do good continually.
Characteristic
Harmony
Truth does not contradict itself. God is not unreliable. All of heavens truths sustain one another. The gospel is everlastingly the same. "What I say unto one I say unto all" (D&C 93:49)
No one receives a revelation telling them to deny Christ, reject his prophets, or their council, to stray from the ordinances, break the covenants...never.
No one receives a revelation that excuses them from the obligation to be obedient to the laws and ordinances of the gospel. This is the doctrine of kindred spirits or the verity that all things seek their own.
D&C 88: 40
40 For intelligence cleaveth unto intelligence; wisdom receiveth wisdom; truth embraceth truth; virtue loveth virtue; light cleaveth unto light; mercy hath compassion on mercy and claimeth her own; justice continueth its course and claimeth its own; judgment goeth before the face of him who sitteth upon the throne and governeth and executeth all things
Characteristic
Warmth
Anyone who has born testimony when they had not planned to do so has somethignin common with the prophet Jeremiah who stated "...But his word was in mine heart as a burning fire shut up in my bones, and I was weary with forbearing, and I could not be stayed." (jer. 20:9)
Here is a good example of not being able to recognize the Spirit of the Lord, from the New testament Luke 24. Two men were walking the Emmaus road. the resurrected Savior appeared to them but they did not recognize him. The scriptures state that their "eyes were holden". He joins in their conversation and talks with them and instructs them for some two hours! These men had the resurrected Jesus Christ as their teacher!
They were not intimidated or uncomfortable. They spoke freely and conversed with him. Ask whatever questions they liked and he answered. "he expounded unto them in all the scriptures the things concerning himself." They get to their destination and sit down to eat, and he breaks bread with them and blesses it and then dissappears.
Only then do they understand the Lord had been with them. They state "Did not our heart burn within us, while he talked with us by the way" Only retrospectivly were they able to look back and discover what they had experienced and realize they had walked with God.
How often have we walked with God, and felt that warmth, but not had the spiritual maturity to recognize it.
Characteristic
Feelings
All true religion brings with it a sense of confidince and assurance, all true religion involves feelings.
Whats a good way to know this? You can't pick up Anti-Mormon literature without reading that we should not trust our feelings. that's a sure sign to know that you should trust them.
Bruce R McConkie stated "All true religion is a feeling."
The first great revelation that Joseph Smith had came while reading the epistle of James. He said "Never did any passage of scripture come with more power to the heart of man than this did at this time to mine. It seemed to enter with great force into every feeling of my heart. I reflected on it again and again".
That is a perfect definition of revelation, And you know it, you just needed it to pointed out to you.
The Spirit of revelation finds eloquence in the feelings of the heart. Christ taught that only those who understood with their hearts could be converted. Teaching Joseph Smith how to understand revelation Christ said "I will tell you in your mind and in your heart" (D&C 8:2) that's a good concept, the Lord doesent give a mindless revelation. "You shall feel that it is right" (D&C 9:8-9)
Laman and Lemuel, consumed by a spirit of rebellion, could not understand spiritual things. Nephi said they were "Past feeling"(1 Nephi 17:45) They could not
feel his words.
Paul taught this as "blindness of the heart" and "past feeling" (Eph 4:18-19) They had darkened their understanding by doing wicked deeds.
Joseph Smith taught if a doctrine is good "It tastes good. I can taste the principles of eternal life, and so can you. They are given to me by the revelations of Jesus Christ; and I know that when I tell you these words of eternal life as they are given to me, you taste them, and I know that you believe them. You say honey is sweet, and so do I. I can also taste the spirit of eternal life. I know that it is good; and when I tell you of these things which were given me by inspiration of the Holy Spirit, you are bound to receive them as sweet, and rejoice more and more."
He was used to feasting on that sort of thing. Alma described it as "Swelling motions which enlarge the soul and become delicious to the taste" (Alma 32: 28)
Characteristic
Inspiration
The Spirit of the Lord is positive, not negative. Any doctrine properly taught and properly understood inspires, lifts. It gives confidence and hope. Paul used the expression "much assurance" (1 Thes. 1: 5) The Plan of Salvation frees the souls of men, it does not bring bondage.
Any doctrine that discourages or oppresses has either been improperly taught or misunderstood. It is
not a characteristic of the doctrines of heaven.
Characteristic
Self reliance
In the revelation given as the preface to the Doctrine and Covenants the Lord testifies that the contents of the Book are "true and faithful". All that is revealed from heaven, whether personal or institutional, is by its nature true and faithful.
Trustworthy, loyalty or fidelity are all roots of the word truth. In the scriptures when we talk about truth its not used in its high spiritual meaning, its something that is standing opposite of error.
The truths of heaven are wholy dependable. "What I the Lord have spoken I have spoken, and I excuse not myself; and though the heavens and the earth pass away, my word shall not pass away"(D&C 1:38)
Here is a man that was accustomed to the spirit of revelation:
Psalms 19:7-11
7 The law of the LORD is perfect, converting the soul: the testimony of the LORD is sure, making wise the simple.
8 The statutes of the LORD are right, rejoicing the heart: the commandment of the LORD is pure, enlightening the eyes.
9 The fear of the LORD is clean, enduring for ever: the judgments of the LORD are true and righteous altogether.
10 More to be desired are they than gold, yea, than much fine gold: sweeter also than honey and the honeycomb.
11 Moreover by them is thy servant warned: and in keeping of them there is great reward.
Latter Day Saints have not just been promised that it is their right to receive revelation. If you pay attention to the scriptural injunction you will discover what is said is that you don't have the right to be without it. Not is it only your right to receive revelation, it is not your right
not to receive revelation. Theres a signifigant difference there. It is our right, it is our obligation.
D&C 121:33
How long can rolling waters remain impure? What power shall stay the heavens? As well might man stretch forth his puny arm to stop the Missouri river in its decreed course, or to turn it up stream, as to hinder the Almighty from pouring down knowledge from heaven upon the heads of the Latter-day Saints.
that's our right, that's our heritage, that's our responsibility.
We can easily forgive a child who is afraid of the dark; the real tragedy of life is when men are afraid of the light. - Plato