Page:An Essay on the Principle of Population (1798).djvu/393

 to the growth of mind. It is probable, that too great, or too little excitement, extreme poverty, or too great riches, may be alike unfavourable in this respect. The middle regions of society seem to be best suited to intellectual improvement; but it is contrary to the analogy of all nature, to expect that the whole of society can be a middle region. The temperate zones of the earth, seem to be the most favourable to the mental, and corporeal energies of man; but all cannot be temperate zones. A world, warmed and enlightened but by one sun, must, from the laws of matter, have some parts chilled by perpetual frosts, and others scorched by perpetual heats. Every piece of matter lying on a surface, must have an upper, and an under side: all the particles cannot be in the middle. The most valuable parts of an oak, to a timber merchant, are not either the roots,