Unfortunately, the people, they do not believe in the next life, although in everyday affair they are experiencing that, "I am eternal. I can remember the days of my childhood. I can remember the days of my youthhood, my boyhood, and I am still working. That means I am continuously there, although my body in different ways have changed." So it is a fact that even after changing this body, you will have another body. Just like you are sitting in this room. Now, if you vacate this room, that does not mean you are finished. You have gone in some other room.
So this is a great science. And people are neglecting this science. They have no, I mean to say, information. There are so many departments in university—technological, medical, engineering, but where is the department to know and understand what is this life, what is God, what is our relationship? So this is not very good civilization.
So there is life after this life. Just like progressive life, a child is progressing to youthhood—the youth is aspiring to become a big man, important man. As in this life there is progressive life, similarly, life after life, there is also progress. There are different grades of life.
So we get information from authoritative books that there are 8,400,000's of different grades of life, and there are 900,000's of aquatic life, 2,000,000 species of plants and trees, about eleven hundred thousand species of life of birds, 3,000,000 types of species of beast and 400,000 species of this human body. Out of that 400,000's, different kinds of human bodies, the civilized body is a great boon. At that time we can make further progress. Either we can transfer to other planets . . . the standard of living, comforts, are many, many thousands times better than this planet.
But in this book, Bhagavad-gītā As It Is, we get information that within this material universe, wherever you go, either you remain in this planet or you go to the moon planet or to the sun planet, or there are millions and trillions of planets . . . the highest planetary system is called Brahmaloka. There the duration of life is very, very great. You cannot calculate even twelve hours of their days. These are described in this book, Bhagavad-gītā As It Is. Sahasra-yuga-paryantam arhad yad brahmaṇo viduḥ (BG 8.17). Four hundred . . . three thousand years is the duration . . . four hundred and, yes, four hundred and three thousands of years, solar years, is the one unit of yuga. Such thousand yugas makes twelve hours of the Brahmaloka planet. Similarly, they live there for a hundred years.
But these four things, namely birth, death, old age and disease, these four things are everywhere, either you live in this planet or moon planet or sun planet or any other planet. The duration of life may be very, very great. Just like in comparison to the ant, our life, human being—we have got hundred years' age—so to the ant it may be very astonishing, "Oh, how such a great length of time one can live?" Similarly, we may be astonished by hearing twelve hours' duration of Brahmaloka, but actually there is. But still, you cannot avoid death. Death is there.
So from this book we understand from the version of Kṛṣṇa, or God that, ā-brahma bhuvanāl lokāḥ punar āvartino 'rjuna (BG 8.16). Even if you go to the highest planetary system, again you have to come back. In this way, all living entities are rotating from one planet to another, from one species of life to another. But we don't want this, actually. If I say that, "If I give you a nice body, youthful body and eternal body, full of knowledge," would you not like to have it? Nobody likes old age, nobody likes death, nobody likes to die, nobody likes to take birth again, enter into the womb of mother and live there ten months. You are tight packed. Nobody likes.
But what is the solution? Is there any solution by the scientist? No scientist can say: "Well, all right, we shall stop death. We shall stop disease." They can manufacture nice medicine to counteract disease, but they cannot manufacture anything which will stop disease. You can fight against death very nicely, but you cannot stop death. These are the problems.