Will man ever be able to retain and maintain the same physical form permanently? To some it would be the height of happiness to realize such an aim, whereas to others it would be a sentence of captivity without hope of release. Is the sage able to prolong his physical life far beyond the normal period? Is there any truth in the Indian legends of yogis who live for a thousand years or more? If not, why should such advanced men lack this power? The answer to the first question is in the negative; to the second question probably in the negative. The answer to the third question is that transiency is the law governing all formed things; that death is the inevitable complement of birth because, as Buddha pointed out, whatever has a beginning in time must likewise have an end in time; and that the truth is that the sage does not really die for he persistently reincarnates in order to help mankind.
-- Notebooks Category 10: Healing of the Self > Chapter 1 : The Laws of Nature > # 57