"The greatest hindrance of understanding rebirth is the strength of our present self-grasping. "I" feels so solid, "me" is this body. And we can´t imagine being anything else. Can you imagine being a baby? We know that.
But the baby state of mind:
Lack of conceptual thought. Lack of knowledge of the world. The inability to express oneself. The inability to understand what´s going on around you.
Can we ever think that we´re like that as a baby ? Hard to imagine. Yet we know for sure that we we´re like that. Then it´s even harder to imagine being in another body, also with a different state of mind."
Ven. Thubten Chodron, från youtube video-serien The easy path to travel to omniscience Part 8.