Every normal crustacean, on the other hand, has the abdominal region of the body covered by a thick chitinous shell. In the Hermits this is represented only by a thin and delicate membrane--of which the sorry figure the creature cuts when drawn from its foreign hiding-place is sufficient evidence. Any one who now examines further this half-naked and woe-begone object, will perceive also that the fourth and fifth pair of limbs are either so small and wasted as to be quite useless or altogether rudimentary; and, although certainly the additional development of the extremity of the tail into an organ for holding on to its extemporized retreat may be regarded as a slight compensation, it is clear from the whole structure of the animal that it has allowed itself to undergo severe Degeneration.
In dealing with the Hermit-crab, in short, we are dealing with a case of physiological backsliding. That the creature has lost anything by this process from a practical point of view is not now argued. It might fairly be shown, as already indicated, that its freedom is impaired by its cumbrous exoskeleton, and that, in contrast with other crabs, who lead a free and roving life, its independence generally is greatly limited. But from the physiological standpoint, there is no question that the Hermit tribe have neither discharged their responsibilities to Nature nor to themselves. If the end of life is merely to escape death, and serve themselves, possibly they have done well; but if it is to attain an ever increasing perfection, then are they backsliders indeed.
A zoologist's verdict would be that by this act they have forfeited to some extent their place in the animal scale. An animal is classed as a low or high according as it is adapted to less or more complex conditions of life. This is the true standpoint from which to judge all living organisms. Were perfection merely a matter of continual eating and drinking, the Am[oe]ba--the lowest known organism--might take rank with the highest, Man, for the one nourishes itself and saves its skin almost as completely as the other. But judged by the higher standard of Complexity, that is, by greater or lesser adaption to more or less complex conditions, the gulf between them is infinite.
We have now received a preliminary idea, although not from the study of a true parasite, of the essential principles involved in parasitism. And we may proceed to point out the correlative in the moral and spiritual spheres. We confine ourselves for the present to one point. The difference between the Hermit-crab and a true parasite is, that the former has acquired a semi-parasitic habit only with reference to _safety_. It may be that the Hermit devours as a preliminary the accommodating mollusc whose tenement it covets; but it would become a real parasite only on the supposition that the whelk was of such size as to keep providing for it throughout life, and that the external and internal organs of the crab should disappear, while it lived henceforth, by simple imbibition, upon the elaborated juices of its host. All the mollusc provides, however, for the crustacean in this instance is safety, and, accordingly in the meantime we limit our application to this. The true parasite presents us with an organism so much more degraded in all its parts, that its lessons may well be reserved until we have paved the way to understand the deeper bearings of the subject.
The spiritual principle to be illustrated in the meantime stands thus: _Any principle which secures the safety of the individual without personal effort or the vital exercise of faculty is disastrous to moral character._ We do not begin by attempting to define words. Were we to define truly what is meant by safety or salvation, we should be spared further elaboration, and the law would stand out as a sententious common-place. But we have to deal with the ideas of safety as these are popularly held, and the chief purpose at this stage is to expose what may be called the Parasitic Doctrine of Salvation. The phases of religious experience about to be described may be unknown to many. It remains for those who are familiar with the religious conceptions of the masses to determine whether or not we are wasting words.
What is meant by the Parasitic Doctrine of Salvation one may, perhaps, best explain by sketching two of its leading types. The first is the doctrine of the Church of Rome; the second, that represented by the narrower Evangelical Religion. We take these religions, however, not in their ideal form, with which possibly we should have little quarrel, but in their practical working, or in the form in which they are held especially by the rank and file of those who belong respectively to these communions. For the strength or weakness of any religious system is best judged from the form in which it presents itself to, and influences the common mind.