Page:An Essay on the Principle of Population (1798).djvu/183

Rh this word to mean, either a constant approach to an unlimited extent, without ever reaching it; or, an increase in the immensity of ages to an extent greater than any assignable quantity.

But surely the application of this term in either of these senses, to the duration of human life, is in the highest degree unphilosophical and totally unwarranted by any appearances in the laws of nature. Variations from different causes are essentially distinct from a regular and unretrograde increase. The average duration of human life will, to a certain degree, vary from healthy or unhealthy climates, from wholesome or unwholesome food, from virtuous or vicious manners, and other causes; but it may be fairly doubted whether there is really the smallest perceptible advance in the natural duration of human life, since first we had Rh