The multitudinous creatures of all kinds which fill the earth, cannot live wholly apart from one another, but are more or less in presence of one another--are interfered with by one another. In large measure the adjustments of acts to ends which we have been considering, are components of that "struggle for existence" carried on both between members of the same species and between members of different species; and, very generally, a successful adjustment made by one creature involves an unsuccessful adjustment made by another creature, either of the same kind or of a different kind. That the carnivore may live herbivores must die; and that its young may be reared the young of weaker creatures must be orphaned. Maintenance of the hawk and its brood involves the deaths of many small birds; and that small birds may multiply, their progeny must be fed with innumerable sacrificed worms and larvæ. Competition among members of the same species has allied, though less conspicuous, results. The stronger often carries off by force the prey which the weaker has caught. Monopolizing certain hunting grounds, the more ferocious drive others of their kind into less favorable places. With plant-eating animals, too, the like holds: the better food is secured by the more vigorous individuals, while the less vigorous and worse fed, succumb either directly from innutrition or indirectly from resulting inability to escape enemies. That is to say, among creatures whose lives are carried on antagonistically, each of the two kinds of conduct delineated above, must remain imperfectly evolved. Even in such few kinds of them as have little to fear from enemies or competitors, as lions or tigers, there is still inevitable failure in the adjustments of acts to ends toward the close of life. Death by starvation from inability to catch prey, shows a falling short of conduct from its ideal. This imperfectly-evolved conduct introduces us by antithesis to conduct that is perfectly evolved. Contemplating these adjustments of acts to ends which miss completeness because they cannot be made by one creature without other creatures being prevented from making them, raises the thought of adjustments such that each creature may make them without preventing them from being made by other creatures. That the highest form of conduct must be so distinguished, is an inevitable implication; for, while the form of conduct is such that adjustments of acts to ends by some necessitate non-adjustments by others, there remains room for modifications which bring conduct into a form avoiding this, and so making the totality of life greater.