If in the duration of life there is any difference, it ought seemingly to be ascribed to the quality of the air. In elevated countries there are commonly found more old people than in low. The mountains in Scotland and Wales, of Auvergne and Switzerland, have furnished more instances of extreme longevity than the plains of Holland, Flanders, Germany, or Poland. In general, however, the period of human existence may be said to be the same in every country. If not cut off by accidental diseases man is found to live to the years of 90 or an 100. Beyond that date our ancestors did not live, nor has it, in any degree varied since the time of David. Should it be asked, why, in the early ages, men lived to 900, 930, and even 960 years? it may, with great probability of reason, be answered, that the productions of the earth might then be of a different nature; as, at the creation, the surface of the globe must have been far less solid and compact than it afterwards became, so it is possible that the productions of Nature, and even the human body itself, being more ductile and more susceptible of extension, their growth was not so soon accomplished as at present. Every kind of nourishment being in itself more soft and more ductile, the bones, the muscles, &c. necessarily retained their primitive softness and ductility longer. As the body, therefore, did not attain its complete expansion, nor its generative powers, for 120 or 130 years, the duration of life would be proportioned to that time, required for the growth, as it is to this day. In the supposition, for example, that the age of puberty was originally at the years of 130, as it is now at the age of 14, it will appear, that the period of human existence has always been proportionally the same as it is at present, since by multiplying those two numbers by seven, for instance, we shall find that the age of the present race will be 98 years, as those in the first age 910. It is probable, then, that the duration of human life decreased in proportion as the solidity of the surface of the earth increased, and that the ages from the creation, to the time of David, having been sufficient to communicate to terrestrial substances all the consistency which they are capable of acquiring by the pression of gravity, the surface of the earth has ever since remained in the same condition, and the limits of the growth of its different productions have been fixed, as well as those of the duration of life.