Such is the start of the counsel given by Vidura to the blind king Dhritarashtra.

Why had sleeplessness overtaken him?

Because Sanjay had taken the king's permission to go sleep!

Because Sanjay had returned from an unsuccessful journey to Upalavya where he had been sent by the king with instructions to not say anything that would incite the Pandavas to war. 

Because, while Sanjay had told Dhritarashtra what he thought, he had still not delivered Ajatshatru's message for the king, which he would do only in the morning.

The morning that was yet to come filled Dhritarashtra with dread.

And thus sleeplessness.

In such a state of unrest, he called for Vidura for words of comfort and wisdom.

Thus begins the five-hundred shloka Prajagara Parva of the Mahabharata, also known as Vidura Niti. In the Bhandarkar Institute's Critical Edition, this parva is part of the Udyoga Parva, and is the fifty-first parva in the hundred-parva classification.

After Vidura comes to the king's inner quarters, Dhritarashtra unburdens to his half-brother that Sanjaya had returned from Upalavya, but had left after berating the king! What little Sanjaya had told the king was enough to fill the king with disquiet. Here is a sample of what Sanjaya tells Dhritarashtra immediately upon his return -

• "At the time of the gambling match, you praised the one whose soul was overtaken by desire."
• "I censure you for discord among the Bharatas. This will lead to the destruction of many beings."
• "O Indra among men! You accepted those who are unworthy."
• "O king! You rejected those who are worthy."
• "Because of the crimes of your deeds, the Kurus will be burnt up, like the one with the black form [fire] burns up dry wood."
• "You have only obtained ill fame."

In any case, it is unsurprising that Dhritarashtra dreaded the morning and Yudhishthira's message. He asked Vidura to comfort him with words of dharma and what led to welfare.

So who is learned? Vidura tells us the signs of the learned:

• One who does not serve that which is censured. 
• He is not an atheist and has faith.
• One whose planned deeds and counsel are not known to others, but are known only after the tasks have been executed
• He whose deeds are not obstructed by cold and heat, fear and affection, prosperity and adversity
• One who wisely follows dharma and artha, and artha over kama for the sake of the hereafter
• If not asked, he does not dabble in the affairs of others.
• He listens patiently. 
• He pursues the objective because of artha, not because of kama. 
• One who does not deviate from his objective because of anger, joy, pride, false modesty and a false sense of vanity
• He decides on a course of action and does not stop before the task has been accomplished. 
• He does not waste time and is in control of his soul.
• They exert to the best of their ability. 
• They act to the best of their ability.
• They do not hanker after the unobtainable. 
• They do not sorrow over what has been lost. 
• They are not deluded in times of adversity.
• They perform tasks that bring prosperity. They do not disregard that which ensures welfare.
• He is not overjoyed because of honours. 
• He is not tormented because of neglect. 
• He is as undisturbed as a pond near the Ganga.
• He knows the nature of men. 
• He learns quickly. 
• He is skilled in words. 
• He can talk about diverse subjects. 
• He can quickly explain what is in the texts.
• His wisdom facilitates his learning. His learning facilitates his wisdom.

Conversely, who is not learned? A person who is not learned is stupid - that much is clear, but Vidura elaborates thus:

• If a person is not learned but vain
• If a person is poor but proud
• If a person strives for artha without performing deeds

A person with these traits is regarded by the learned as stupid.