In one of the Vedic _Upanishads (Oupnekhat_, II.) _the natural length_ of human life is put down at one hundred years. And I believe this to be right. I have observed, as a matter of fact, that it is only people who exceed the age of ninety who attain _euthanasia_,--who die, that is to say, of no disease, apoplexy or convulsion, and pass away without agony of any sort; nay, who sometimes even show no pallor, but expire generally in a sitting attitude, and often after a meal,--or, I may say, simply cease to live rather than die. To come to one's end before the age of ninety, means to die of disease, in other words, prematurely. Now the Old Testament (Psalms xc. 10) puts the limit of human life at seventy, and if it is very long, at eighty years; and what is more noticeable still, Herodotus (i. 32 and iii. 22) says the same thing. But this is wrong; and the error is due simply to a rough and superficial estimate of the results of daily experience. For if the natural length of life were from seventy to eighty years, people would die, about that time, of mere old age. Now this is certainly not the case. If they die then, they die, like younger people, _of disease_; and disease is something abnormal. Therefore it is not natural to die at that age. It is only when they are between ninety and a hundred that people die of old age; die, I mean, without suffering from any disease, or showing any special signs of their condition, such as a struggle, death-rattle, convulsion, pallor,--the absence of all which constitutes _euthanasia_. The natural length of human life is a hundred years; and in assigning that limit the Upanishads are right once more.] A man's individual career is not, as Astrology wishes to make out, to be predicted from observation of the planets; but the course of human life in general, as far as the various periods of it are concerned, may be likened to the succession of the planets: so that we may be said to pass under the influence of each one of them in turn. At ten, _Mercury_ is in the ascendant; and at that age, a youth, like this planet, is characterized by extreme mobility within a narrow sphere, where trifles have a great effect upon him; but under the guidance of so crafty and eloquent a god, he easily makes great progress. _Venus_ begins her sway during his twentieth year, and then a man is wholly given up to the love of women. At thirty, _Mars_ comes to the front, and he is now all energy and strength,--daring, pugnacious and arrogant. When a man reaches the age of forty, he is under the rule of the four _Asteroids_; that is to say, his life has gained something in extension. He is frugal; in other words, by the help of _Ceres_, he favors what is useful; he has his own hearth, by the influence of _Vesta_; _Pallas_ has taught him that which is necessary for him to know; and his wife--his _Juno_--rules as the mistress of his house.