First of all you have to believe that the soul transmigrates. That's a fact. That we are doing every day, every minute... Simply it requires little brain. Dhīra. Dhīras tatra na muhyati. Tathā dehāntara-prāptir dhīras tatra na muhyati (BG 2.13). Dhīra means sober. What is the difficulty to understand? I was a child, you were a child. Just like these children, talking without any meaning. But they are children, they are excused. But the same child will become a young man, old man. The body has changed. Just like I was also child, you were also child. In childhood we have done so many nonsense things. But in this body I am not doing anything. I have to consider.
So that means the body is different. According to the body... The rascal says that the animals have no soul. Why? Then the child has no soul? What is the difference between the child's behavior and an animal's behavior? Anyone who has got a dog in the family, the dog is also one of the children. He also behaves... The children also behave like the dog. And the children do not find any difference, that a dog is different, he is different. Simple. So if the dog has no soul and if the behavior are the same, as of the dog of the child, so does it mean the child has no soul? How foolish they are. Just see. And they say the animal has no soul. Why? You can say, "The intelligence is not developed." As the child's intelligence is not developed, it will develop with the chance of the body, similarly, the dog also will have developed sense when he will change his dog's body to human body. That is called evolution. He will get the chance. Nature will give the chance.