H6 A V IS INERT IAE

hypothesis stands now; but it is enough tohave mentioned this here, since it will comein afterward,

XXIII. We shall conclude the necessity ofthe resistance of matter with greater evidence,see the connexion it hath with solidity itself,and therefore be more familiarly convincedof it, if we observe what use it is of both inour own and other animal bodies, in one pai>ticular respect, viz, that of progrejstve mo-tion and from thence infer with respect toother motions both in animate and inanimatebodies. Though our bodies did not at allgra-vitate to the earth, nor were supported by it,as a solum , or snstentacle, yet the resistanceit affords would be still absolutely necessaryto our progrejstve motion , Every step we make,we push the earth from behind us, with ourhindmost foot, to wit, and the resistance itmakes, since action and re-action are equal,gives us our propensity, and drives us for-ward : whereas if it were unresisting matter,we should never be able to move, or even tocreep, from one place to another. For eitherthe earth would yield from our foot pushing,without communicating any action or forceso it, and leave us disappointed of our aim,'

sq