This particular story has two stories rolled into one. Once Kubera’s twin sons Nalakubara and Manigriva were cursed by Sage Narada (they must have done something really vile for the normally sweet tempered Narada to lose it, but that’s a different story) to be born as two Arjuna (Terminalia Arjuna) trees and spend 100 years before they would be liberated from their curse. These two incarnated as twin Arjuna trees in the region of Vraja (Gokula) close to where Krishna lived with his foster parents – Yashoda and Nanda.
Little Krishna was a restless and naughty child. He simply couldn’t and wouldn’t stay at one place. He would not allow his mother Yashoda to concentrate on her daily duties. He was always up to some mischief.
One day little Krishna was particularly naughty and mischievous. Yashoda at her wits end tied him up with a rope to a large stone mortar so that he would stay at one place and she could get back to churning curds for butter.
Krishna as soon as he saw his mother was out of sight, started walking towards the Arjuna trees with the large stone mortar trailing behind him. These twin trees had rooted themselves close to one another with only a small interspace between them. Little Krishna squeezed himself through the interspace but the stone mortar got stuck crosswise between the twin Arjuna trees.
Little Krishna pulled the mortar with all his strength and with such force that the two great trees cracked in the middle, their roots were uprooted and they fell to the ground with a loud crash. Nalakubara and Manigriva were liberated and they went back to their heavenly abode.
Although a simple story, as with all puranic stories it contains a symbolic expression of a profound truth:
The two trees symbolize the apparent duality of existence between the real and the unreal – the jeeva/atman (individual) and the paramatman (Supreme). The mortar crashing against the trees is the sudden shattering of the illusion of duality. The uprooted trees and liberation of the twins of Kubera are symbolic of the liberation of the atman from its attachment to the gross world and realization of the supreme indwelling principle within…
Also symbolic is the use of the “Arjuna” trees to tell this story. It could have been any other tree but then wasn’t the Bhagavad Gita recited to the warrior “Arjuna” by Sri Krishna on the battlefield of Kurukshetra?