In the kaiśora age, beginning from the eleventh year and continuing up to the end of the fifteenth year, Kṛṣṇa's arms, legs and thighs became marked with three divisional lines. At that time Kṛṣṇa's chest challenged a hill of marakata jewels, His arms challenged pillars of the indranīla jewel, the three lines of His waist challenged the waves of the River Yamunā, and His thighs challenged beautiful bananas. One gopī said, "With all these exquisite features of His body, Kṛṣṇa is too extraordinarily beautiful, and therefore I am always thinking of Him to protect me, because He is the killer of all demons."
The idea expressed in this statement is that the gopīs were comparing their attraction for Kṛṣṇa to an attack by demons; and to counteract their attraction for the beauty of Kṛṣṇa, they were also turning to Kṛṣṇa hopefully, because He is the killer of all kinds of demons. In other words, they were perplexed, because on one hand they were attracted by the beauty of Kṛṣṇa, and on the other they needed Kṛṣṇa to drive away the demon of such attraction.
This kaiśora age can be translated as adolescence. At the end of this period all the gopīs said, "Kṛṣṇa is the killer of the attraction of Cupid, and as such He disturbs the patience of all newly married girls. Kṛṣṇa's bodily features have become so exquisite—it is as if they were all manifesting an artistic sense of the highest sort. His dancing eyes have dimmed the brilliance of the most expert dancer, and so there is no longer any comparison to the beauty of Kṛṣṇa." Learned scholars therefore describe the features of His body at this time as nava-yauvana, newly invented youthfulness. At this stage of Kṛṣṇa's bodily features, the conjugal love affairs with the gopīs and similar pastimes become very prominent.
There are six features of conjugal love affairs, called peacemaking, picking a quarrel, going to meet one's lover, sitting together, separation and support. Lord Kṛṣṇa expanded an empire of these six features, of which He was the ruling prince. Somewhere He was picking quarrels with the young girls, somewhere He was scratching them with the nails of parrots, somewhere He was busy going to visit the gopīs, and somewhere He was negotiating through cowherd friends to take shelter of the gopīs.
Some of the gopīs addressed Him thus: "Dear Kṛṣṇa, because of Your adolescent age, You have just become the spiritual master of these young girls, and You are teaching them to whisper among themselves. You are teaching them to offer solemn prayers, as well as training them to cheat their husbands and to join You in the gardens at night, without caring for the instructions of their superiors. You are enthusing them by the vibration of Your enchanting flute; and, as their teacher, You are teaching them all the intricacies of loving affairs."
It is said that even when Kṛṣṇa was a boy of five He manifested such youthful energies, but learned scholars do not explain them because of the absence of suitable age. Kṛṣṇa was beautiful because every part of His body was perfectly arranged without any defect. Such perfect bodily features of Kṛṣṇa are described as follows: "My dear enemy of Kaṁsa, Your broad eyes, Your rising chest, Your two pillarlike arms and the thin middle portion of Your body are always enchanting to every lotus-eyed beautiful girl." The ornaments on the body of Kṛṣṇa were not actually enhancing His beauty, but just the reverse—the ornaments were beautified by Kṛṣṇa.
A person is called mild when he cannot even bear the touch of the most soft thing. It is described that every part of Kṛṣṇa's body was so soft that even at the touch of newly grown leaves, the color of the touched part of His skin would change. At this kaiśora age, Kṛṣṇa's endeavors were always bent toward arranging the rāsa dance, as well as toward killing the demons in the forest of Vṛndāvana. While Kṛṣṇa was engaged in enjoyment with the boys and girls within the forest of Vṛndāvana, Kaṁsa used to send his associates to kill Kṛṣṇa, and Kṛṣṇa would show His prowess by killing them.