What is the true and proper outlook towards weakness leaving the body?
Nature therefore forms all creatures with the same power, and after the same standard, in the present day, as in ages past; and we must not ascribe our physical degeneracy in the least to any alteration in her laws, and her energy, but to contingent causes: that is to a defective development of the germe, through the fault of our parents, and of circumstances; to deteriorating education; to a debilitating way of life; and sometimes to disadvantages of climates.
Thus all the weakness of the present refined race of men is only individual weakness: and even that we may term hereditary, when the weaknesses and defects of parents are entailed upon their children, is nothing but the continued operation of the accidental impression.
Consequently, in proportion as these contingent causes, and their operation, are removed, nature will proceed to fashion men after her original rule.
-Johann Christoph Friedrich Guts Muths, Gymnastics for Youth, 1803, pg. 26-27.