The life expectancy of a cat is about 12 years.  The popular notion is that one cat year is the equivalent of seven man years, but like so many human pronouncements about cats it is (1) interesting and (2) inaccurate.
The usual allotment of 12 years seems to be enough time for the cat to do all she might care, or reasonably expect, to do, and is quite long enough for her to become a fixture in human lives and for sadness to be felt at her departure.

The cat begins life as an appealingly helpless little critter, blind, deaf and toothless. Its four-inch body wears a first thin coat of fur, marked and colored in the pattern which will distinguish it as an adult. .
The kitten is soon able to smell and taste, and then hear. The eyes remain tightly closed, however; sight is still a week or so away. The kitten eats and sleeps — a completely self-centered existence, warm, soft and nourishing.

The opening eyes are blank and blue, and will be highly sensitive to strong light for some days to come. As a rule, the eyes open in anywhere from eight days to two weeks, and are adaptable to extremes of light and dark at a month or five weeks. But the timing in these developments is subtle and very much up to the individual. Once it can see, the kitten naturally seems perkier, although it actually is still very limited in its capacity to support itself and move around.