The Upanishads are teachings from the four Vedas of Hinduism. The word in Sanskrit when translated into English means "to sit near". In the ancient times the teacher used to sit on a raised platform and the students used to sit on the ground. Originally it was passed on orally till writing Sanskrit took effect. There are major and minor Upanishads.
The three stories are from the Upanishads (or Vedanta or "the end of the Veda").
The first story is that of young Nachiketa, who struggles to comprehend the truth of life and death. He approaches Yama, the God of Death, and is tested by the Lord before found worthy of divine instruction.
The second story is about Satyakama's search for the ultimate reality or "Brahman". Here, nature is the best teacher as Satyakama experiences Brahman directly rather than through verbal instruction by his guru, Gautama.
the story of Satyakama
Long ago, in the Chandogya Upanisad, sage Gautama accepted Satyakama (a lad with lowly social status and son of a sudra prostitute) as his student for becoming a brahmin based on certain important qualities, which still remain valid today and can be used for selecting and training present-day non-brahmin priests and temple worshippers.
One day the boy Satyakama came to his mother and said, “Mother, I want to be a religious student. What is my family name?”
“My son,” replied his mother, “ I do not know. In my youth I was a servant and worked in many places. I do not know who was your father. I am Jabala, and you are Satyakama. Call yourself Satyakama Jabala.”
Thereupon the boy went to Gautama and asked to be accepted as a student. “Of what family are you, my lad?” inquired the sage.
Satyakama replied, “ I asked my mother what my family name was, and she answered: ‘I do not know. In my youth I was a servant and worked in many places. I do not know who was your father. I am Jabala, and you are Satyakama. Call yourself Satyakama Jabala!’ I am therefore Satyakama Jabala, Sir.”
Then said the sage, “None but a true brahmin would have spoken thus. Go and fetch fuel, I will teach you. You have not swerved from the truth.”
Satyakama did not hide facts about his family, nor did he try to give any wrong or misleading information. This thing impressed Gautama a great deal. In addition, Gautama (a brahmin himself) was not judgmental towards Satyakama or his mother, and he showed a lot of compassion and consideration towards them by not discriminating against Satyakama.
In the third story, Prajapati (Sanskrit: “Lord of Creatures” or Brahma) - the father, the guru and the guide - utters a single syllable "DA" as instruction to the dissatisfied gods, humans and demons who are seeking contentment and peace. "DA" was understood and interpreted differently by the pupils in light of their own experiences.
These three stories are, in essence, about the guru and the pupil, where one who embarks on the path of true knowledge surely achieves it.
Many many thanks to “Ajnaabi” for providing ACK.