the kid is too young. As parents, the emphasis should be placed up moral education. Show the kid how to treat other people well and how to be strong in difficulties. You can wait for the kid to get more mature. One risk of delving into high philosofy is this: An impersonal philosophy can be misunderstood to be solipsism.
For example, when I say: "I am transcending the universe, transcending God concept and transcending any concept" it can be misunderstood as the personal EGO to be bigger than universe, bigger than God and etc. The "I" in my sentence is not personal EGO but the transcending SELF, teenagers may not have philosohical training to properly understand.
Even most adults don't have the proper intellect to understand that, let alone young children.
So, focus on moral education, leave the phisophy later when he becomes an adult, when he grows up, as father you can introduce a few books for him to read when he is down in hardship. If he is ready for such philosophy because of his KARMA, he may get it very quickly. No need to worry about it when he is only 15.
