For example...

For example, it is logically impossible to divide three oranges into two equal parts without cutting anyone of them. It is self-evident that, three being an odd number, it is not divisible into two whole numbers. Only an even number can be so divided and the same number cannot be both odd and even simultaneously, because that will mean self-contradiction which is impossible.

But a man's entering into fire without being hurt or going to the sun without being affected by its heat is not logically impossible, for it is not self-contradictory to suppose that heat does not pass. from a body having a higher temperature to a body having a lower temperature. Only experience has proved that if two bodies are mixed or put together, heat passes from a body having higher temperature to a body having lower temperature, till the temperature of both the bodies is at par.

Thus, we know that the scope of the logical possibility is wider than that of the scientific possibility and the scope of the scientific possibility is wider than that of the practical possibility. There is no doubt that a person's remaining alive for thousands of years is not logically impossible, for there is nothing irrational or self-contradictory about it. Life itself does not imply the sense of quick death.

Admittedly, such a long life is not as practical as descending to the bottom of the sea or ascending to the moon. Notwithstanding the present scientific facilities it has not so far been possible to prolong human life to hundreds of years. Even those who have all the modern facilities at their disposal and are the keenest to continue to live cannot have more than the normal span of life. As for the scientific possibility there exists nothing to justify its denial from a theoretical point of view.

In fact this question is related to the physiological explanation of senility. The question is, whether there exists a natural law according to which human tissues and cells, after attaining the stage of full development, automatically begin to stiffen and degenerate, till they cease functioning at a particular moment or the senile degeneration is caused by some external factors, such as microbes and poisons infiltrating into the body through polluted food, unhealthy jobs or some other causes.

It is a question with which science is grappling at present and is earnestly trying to find an answer to it. For the present there is more than one scientific explanation of senility.