“Should a candle be put under a bushel or under a bed? ...” (Mark 4:21-23)

“Should a candle be put under a bushel or under a bed? And not set upon a candlestick? Because there is nothing concealed that will not become apparent – nor was anything kept secret that won't come out. Anyone who has ears to hear with should listen.” (Mark 4:21-23)
Jesus is explaining the importance of becoming aware of the reality of things. He is speaking of learning about our relationship with the Supreme Being.

What does putting a candle 'under a bed' mean?

Jesus' analogy - putting a candle under a bed - is about hiding the Truth. It is a question of ignorance or revelation. Ignorance means to hide from reality. Revelation means to face reality. It means to learn about reality - and then deal with it.

Many of us are hiding from reality. We don't want to face the reality of our situation with regard to who we are, what our purpose is and why we are here. Some of us want to know but simply do not know. For those of us, Jesus promises that all will be revealed.

If we want to know the reality of our situation, Jesus is saying that we need to carefully study his teachings, especially with regard to our identity and our relationship with God.

Why is our identity important?

Jesus taught that we are not these physical bodies. He taught that we will not be happy within the physical world because we are spiritual beings - children of the Supreme Being.

This concept is often missed by some teachers, but it is nonetheless what Jesus taught. Consider these statements:
"For this reason I say to you, don’t be anxious about your life, as to what you will eat or what you will drink; nor for your body and what you will wear. Is not the soul more than food, and the body more than clothing?" (Matt. 6:25)
"And don’t fear those who can kill the body but are unable to kill the soul." (Matt. 10:28)
"I tell you my friends, don’t be afraid of those who kill the body and after that, can do nothing more." (Luke 12:4)
Jesus is distinguishing our self - the soul - from our temporary physical body. The reason why he is saying they can't do anything more after the body is killed is because each of us - the soul - lives on after the body dies.

Jesus was even more clear in some of his statements in other Gospels (see Lost Gospels of Jesus):
Jesus said, “One realizes the material world through the physical body. But for one who occupies the physical body, the material world is not satisfying.” (Gospel of Thomas, 80:1-2)
Jesus said: “You are pleased when you look upon your reflection. But when you see your true self that existed before your body, and never dies nor becomes visible, how can you bear it?” (Gospel of Thomas 84:1-4)
The Master replied, “James, don’t worry about me or these people. I am the self within the body. I didn’t suffer at all, nor was I in distress. So these people have not harmed me. (Gospel of James the Grieving, Verse 28)
The Savior said, “The light of the body is the soul. So long as what is within you becomes a priority, then [missing text] your body becomes illuminated. (Dialogue of the Savior, Verse 10)
Matthew said, “Master, I would like to see that dwelling place where there is no wickedness, but rather, there is only pure illumination!” The Master replied, “Brother Matthew, you won’t be able to see it so long as you are carrying around a physical body.”  (Dialogue of the Savior, Verses 32-33)
"One who doesn’t know the wind is blowing will get blown away with it. If one doesn’t know about the separate existence of the body, he will die with it.  (Dialogue of the Savior, Verse 42)
"But when the spiritual soul was cast within the physical body, she became a companion of lust, hatred and enviousness, and the materialistic mind. Thus the physical body manifested through lust, and lust manifested from materialism. It is for this reason that the soul became their companion." (The Authoritative Teaching, Verses 7-8)
“Watch and pray that you don’t continue to exist within the flesh. But rather, that you rise from the bondage of this bitter life. And as you pray, you will find peace, for you have departed from the suffering and the degradation. For when you depart from the sufferings and lusts of the body, you will receive peace from the Devoted One, and you will share the dominion of the Supreme Being, and become united with Him – and He with you – from now on, for eternity,” (Book of Thomas the Contender Page 145)
We don't have a soul - each of us is a soul. This is our spiritual composition. This soul leaves the body at the time of death.  Where we go after the body's death depends upon our consciousness.

What is our composition?

Because Jesus was teaching that the physical world and all its trappings do not bring happiness. This is why Jesus said:
“Follow me, and let the dead bury their dead,” replied Jesus. (Matt. 8:22)
Jesus is comparing the identification of the self as the physical body to being spiritually dead here. It is a metaphorical use of the word "dead." A person's physical body may die, but a person can be spiritually dead if we are not living within our actual identity - our spiritual identity. Jesus says it another way in Luke:
“Let the dead bury their dead. But as for you, go and preach the sanctuary of God.” (Luke 9:60)
What does "preach the sanctuary of God" mean?

The word "sanctuary" is being translated from the Greek word βασιλεία (basileia). This is often translated to "kingdom" 
in many translations. However, the Greek word means, according to the lexicon, "royal power, kingship, dominion, rule - not to be confused with an actual kingdom but rather the right or authority to rule over a kingdom." So why would they translate it to the kingdom if the word doesn't relate to an actual kingdom?

It means accepting the superiority - the sanctuary - of the Supreme Being. The Supreme Being is the most powerful, beautiful, gracious, loving and compassionate person. The Supreme Being is our Best Friend and we can rely upon Him. We can take refuge - or sanctuary - of Him. This is preaching the "sanctuary of God."

Is this what Jesus did?

He preached the excellent nature of the Supreme Being. He preached that we can take shelter in the Supreme Being. He preached that we can love the Supreme Being and give our heart to the Supreme Being:
“The most important of all the instructions is, ‘Hear O Israel – the LORD our God is our only Lord –and you shall love the LORD your God with all your heart, with all your soul and with all your mind and with all your strength’ – this is the most important instruction." (Mark 12:30)
Love is not a vague thing. It is part of a relationship between two individuals: Love requires a lover and a beloved. This means that the Supreme Being is a Person - a Person who can be loved and served: A lovable Person.

This information - that we are spiritual in essence and the Supreme Being is lovable - uncovers the truth about our existence and purpose. And if we can give our hearts to God, we will be acting upon that knowledge.