greater force in the work itself, are sufficient to establish the
indefinite perfectibility of man upon the supposition of the same
natural faculties and the same organization which he has at present,
what will be the certainty, what the extent of our hope, if this
organization, these natural faculties themselves, are susceptible of
amelioration?

From the improvement of medicine, from the use of more wholesome food
and habitations, from a manner of living which will improve the
strength of the body by exercise without impairing it by excess, from
the destruction of the two great causes of the degradation of man,
misery, and too great riches, from the gradual removal of transmissible
and contagious disorders by the improvement of physical knowledge,
rendered more efficacious by the progress of reason and of social
order, he infers that though man will not absolutely become immortal,
yet that the duration between his birth and natural death will increase
without ceasing, will have no assignable term, and may properly be
expressed by the word 'indefinite'. He then defines 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 have had any authentic history of man. The prejudices of
all ages have indeed been directly contrary to this supposition, and
though I would not lay much stress upon these prejudices, they will in
some measure tend to prove that there has been no marked advance in an
opposite direction.

It may perhaps be said that the world is yet so young, so completely in
its infancy, that it ought not to be expected that any difference
should appear so soon.

If this be the case, there is at once an end of all human science. The
whole train of reasonings fro