The fourth Niyama is Swadhyaya. Swa means ‘self’, Adhyaya means ‘inquiry’ or ‘examination’.
Guru Dronacharya was the royal Guru (teacher) of the Pandavas and Kauravas. He used to teach military art to the princes.
Once, a boy named Ekalavya asked Guru Dronacharya, "Gurudev, will you teach me the art of archery?" Ekalavya aspired to study archery in the gurukul of Dronacharya, the greatest known teacher. Dronacharya was in a dilemma as he had promised King Bhishma that he will teach this art only to the princes. Ekalavya was not a prince, so Dronacharya was hesitant to teach him and he duly conveyed his refusal to Ekalavya.
Deeply sad by Dronacharya's rejection, Ekalavya returned home. However, he was determined to master the art of archery. So, he went into the forest and prepared a clay statue of Guru Dronacharya. He accepted the statue as his Guru and practiced archery in front of it every single day. After practicing for years together, Ekalavya eventually became an exceptional archer.
Once Guru Dronacharya took the Pandava and Kaurava princes to the forest for practicing archery. A dog was also accompanying them. The dog wandered away from the place of practice and deep in the forest, came across Ekalavya and started barking at him. Disturbed in his practice by the dog, Ekalavya aimed seven arrows in the dogs mouth with such caution and skill that it stopped his barking without injuring the dog. The dog returned to the place where the princes were practising.
Dronacharya was amazed to see the dog's state. He was wondering how such a success could be achieved. Dronacharya and his students investigated, and came upon Ekalavya, practicing archery. On seeing Dronacharya, Ekalavya was filled with joy. He bowed down to him.
Dronacharya asked Ekalavya, "Where did you learn archery?". Pointing towards the clay statue, Ekalavya replied, "Under you, O Guru." Ekalavya had learnt archery by self introspect and effort with immense devotion and reverence towards his Guru Dronacharya.
From the above, story of Ekalavya we can understand how he got mastery over archery through his Swadhyaya or self introspect.