"Krishna is beautiful at His different ages -- namely His childhood, His boyhood and His youth. Out of these three, His youth is the reservoir of all pleasures and is the time when the highest varieties of devotional service are acceptable. At that age, Krishna is full with all transcendental qualities and is engaged in His transcendental pastimes. Therefore, devotees have accepted the beginning of His youth as the most attractive feature in ecstatic love.
"At this age Krishna is described as follows: 'The force of Krishna's youth was combined with His beautiful smile, which defeated even the beauty of the full moon. He was always nicely dressed, in beauty surpassing even Cupid, and He was always attracting the minds of the gopis, who were thereby always feeling pleasure.'"