Before the bird was ever placed in the tree, Droṇa had already noticed something about Arjuna. The princes received the same instruction, but Arjuna stayed close to his teacher, practised constantly, and became unusually quick with the bow.
One evening, while Arjuna was eating, the lamp went out in the wind. His hand still found its way to his mouth by habit. The text says that this made him think about what practice could do, and he began practising archery at night as well.
Droṇa heard the bowstring in the darkness and came to him. From then on, the teacher was certain that Arjuna's persistence was setting him apart.
Later, when the princes' education had been completed, Droṇa decided to compare his pupils directly.
Before calling them together, he had an artificial bird placed at the top of a nearby tree. Then he ordered the students to stand ready with bows bent and arrows fitted. When he gave the command, each was to cut off the bird's head.
But the command did not come immediately.
First came a question.
Yudhiṣṭhira was called forward. Droṇa asked whether he could see the bird.
Yes.
Could he also see the tree? Droṇa himself? His brothers?
Yudhiṣṭhira said that he could see the tree, himself, his brothers and the bird.
Droṇa asked again. The answer remained the same.
So Yudhiṣṭhira was told to stand aside. He was not allowed to shoot.
Droṇa repeated the test with Duryodhana, the other sons of Dhṛtarāṣṭra, Bhīma, and the rest of the pupils, including princes who had come from other lands to study with him.
Their answers were much like Yudhiṣṭhira's. They saw the teacher, the tree, the other students and the target. One after another, they were sent aside.
Nothing they named was imaginary. The tree really was there. Their teacher really was standing nearby. Their fellow students really were watching.
Then Droṇa called Arjuna.
Arjuna stood with the bow bent and the arrow ready.
Do you see the bird?
Yes.
Do you see the tree?
No.
Do you see me?
No.
Arjuna said that he saw the bird only.
Droṇa narrowed the question once more. If you see the bird, describe what you see.
Arjuna answered that he could see only the bird's head, not its body.
The source says that Droṇa was so delighted that the hair on his body stood on end.
Now he gave the command.
Shoot.
Arjuna released the arrow. It struck off the artificial bird's head and brought it down from the tree.
Droṇa embraced him. The test was over.
The episode is often retold with the line I see only the eye. That is not what the K.M. Ganguli witness says. In this text, Arjuna first says that he sees the bird, and when pressed again he says that he sees only its head.
That difference is worth keeping because it shows attention tightening in stages. The target becomes smaller as the question becomes more exact.
The lesson is not that everything outside the target has ceased to exist. Every student knows the tree and teacher are still there.
It is that a chosen task can become clearer when the mind stops carrying everything else into the same instant.
The bird test also comes after a training period in which Droṇa had taught Arjuna to fight from horseback, from an elephant, from a chariot and on the ground, and to use several kinds of weapons. The test is not measuring whether he has learned one trick with one bow. It comes after a broad education in arms.
After Arjuna's arrow brings the head down, Droṇa clasps him to his chest. In the text, the teacher immediately thinks ahead to the conflict with Drupada that has long been in his mind.
Arjuna's concentration is not treated as a classroom ornament; Droṇa sees it as proof of what this pupil may be able to do when a real task comes.
Arjuna's answer becomes smaller and smaller until it is exactly the size of the thing he has to do.