that "friction excites the appetite of bodies for contact, which appetite does not like air much, but prefers something else which is tangible." The phenomena of chemical affinity and the like were also explained, precisely as Campanella or Cardan would account for them, by the delight in mutual contact, _i.e._ by an inherent sensibility, and desire or striving of like towards like.[621] In both Bacon and Bruno, also, this universal animism is combined with an atomistic theory of mechanical nature, and with the belief that no physical phenomenon is understood until it can be expressed in mathematical terms: "the more our inquiry inclines to simple natures, the plainer and clearer shall things become; for we shall have to deal with the simple instead of the manifold, the computable instead of the surd, the definite and certain instead of the vague,--as in the elements of letters, and the notes of harmonies, and an inquiry is best conducted when the physical is defined by the mathematical."[622] The last result of analysis is not, with either Bacon or Bruno, the atom of the Epicurean physics, viz. an immutable substance floating in empty space; but Bacon's _particulae verae_ are much more confusedly thought out than the Italian's theory--of a subtle ethereal matter diffused throughout the universe, and of the denser atoms which are in constant motion within it. There is, however, the same perpetual flux and reflux in matter with Bacon as with Bruno.[623] In the last resort, Bacon took refuge in a hope of future explanation--always, however, by simple, positive, computable factors--regarding atoms and void, as on a par with _materia prima_, human abstractions, entirely unfruitful, not light-bringing "anticipations of nature." In regard to the relation between the human understanding and nature, both had absolute convictions of the power of the former, directed by the rules of experience and limited by the data of sensation, to comprehend the latter; but while Bruno saw in the negative limits of the understanding a positive hint of a reality beyond, the more careful Bacon saw only a further ground for falling back from reason upon faith. Thus the incapacity of the mind to rest in any finite space, without thinking of a space beyond that and beyond, or of imagining a body than which none could be greater, was proof to Bruno that space itself was infinite, and that body or matter was immeasurable, _i.e._ infinite in extent and in quantity. Bacon also makes use of this impossibility in the human intellect of resting, acquiescing, at any point as a finality. "It must ever pass beyond--but it is in vain. Thus it is unthinkable that there should be any extreme or outermost rim to the world, our mind always of necessity thinks there may be something beyond: nor can we think how eternity could have flowed down to this day: the distinction between an infinity _a parte ante_ and an infinity _a parte post_ cannot be