"The Buddha refused to have any dealings with those things which don't lead to the extinction of Dukkha. Take the question of whether or not there is rebirth. What is reborn? How is it reborn? What is its kammic inheritance? (kamma-is volitional action by means of body, speech or mind.) These questions are not aimed at the extinction of Dukkha. That being so, they are not Buddhist teaching and they are not connected with it. They do not lie in the sphere of Buddhism. Also, one who asks about such matters has no choice but to indiscriminately believe the answer he is given, because the one who answers is not going to be able to produce any proofs, he's just going to speak according to his memory and feeling. The listener can't see for himself and so has to blindly believe the other's words. Little by little the matter strays from Dhamma until its something else altogether, unconnected with the extinction of Dukkha."