The machine is so nice that we are thinking that it is growing. It is not growing—all different bodies, all different, every moment, every second. That is the scientific. The blood corpuscles are changing, and the body is different.
So this is the preliminary knowledge of advancing in spiritual knowledge. You do not know what is spirit - and what is the spiritual knowledge? This is spirit. That spirit is there. Asmin dehe, in this body, there is the spirit soul, and the spirit soul is permanent. The spirit soul is permanent, and it is expressing in different way according to the change of body. Just like this child is now just like ordinary animal. But this body, when he will change, he will express in a different way. He will express in a different way. Similarly, if you get the cat's body, you will express in a different way. If you get a dog's body, you will express in a different way. If you get the body of a tree, that you cannot express. You will have to stand simply. You have to suffer. You cannot protest. Somebody is taking, cutting, take your fruit, cutting your branch, but you cannot protest.
So this is going on perpetually. Not perpetually—at least for many, many millions of years, for many, many millions of years. But we are, because we are fool, especially in this age of Kali, we do not understand it.