this, a certain sanction is acquired for-such conduct. The preservation of the species being the ultimate end, it results that where an occasional mortality of individuals in defense of the species furthers this preservation in a greater degree than would pursuit of exclusive benefit by each individual, that which we recognize as sub-human justice may rightly have this second limitation.
It remains only to point out the order of priority, and the respective ranges, of these principles. The law of relation between conduct and consequence, which, throughout the animal kingdom at large, brings prosperity to those individuals which are structurally best adapted to their conditions of existence, and which, under its ethical aspect, is expressed in the principle that each individual ought to receive the good and the evil which arises from its own nature, is the primary law holding of all creatures; and is applicable without qualification to creatures which lead solitary lives, save in that self-subordination needed among the higher of them for the rearing of offspring.
Among gregarious creatures, and in an increasing degree as they co-operate more, there comes into play a law, second in order of time and authority, that those actions through which, in fulfillment of its nature, the individual achieves benefits and avoids evils, shall be restrained by the need for non-interference with the like actions of associated individuals. A substantial respect for this law in the average of cases being the condition under which alone gregariousness can continue, it becomes an imperative law for creatures to which gregariousness is a benefit. But, obviously, this secondary law is simply a specification of that form which the primary law takes under the conditions of gregarious life; since, by asserting that in each individual the interactions of conduct and consequence must be restricted in the specified way, it tacitly reasserts that these interactions must be maintained in all other individuals.
Later in origin, and narrower in range, is the third law, that under conditions such that, by the occasional sacrifices of some members of a species, the species as a whole prospers, there arises a sanction for such sacrifices, and a consequent qualification of the law that each individual shall receive the benefits and evils of its own nature.
Finally, it should be observed that whereas the first law is absolute for animals in general, and whereas the second law is absolute for gregarious animals, the third law is relative to the existence of enemies of such kinds that, in contending with them, the species gains more than it loses by the sacrifice of a few members; and in the absence of such enemies this qualification imposed by the third law disappears.