In the eyes of Nature this was a twofold crime. It was first a disregard of evolution, and second, which is practically the same thing, an evasion of the great law of work. And the revenge of Nature was therefore necessary. It could not help punishing the Sacculina for violated law, and the punishment, according to the strange and noteworthy way in which Nature usually punishes, was meted but by natural processes, carried on within its own organization. Its punishment was simply that it was a Sacculina--that it was a Sacculina when it might have been a Crustacean. Instead of being a free and independent organism high in structure, original in action, vital with energy, it deteriorated into a torpid and all but amorphous sac confined to perpetual imprisonment and doomed to a living death. "Any new set of conditions," says Ray Lankester, "occurring to an animal which render its food and safety very easily attained, seem to lead as a rule to degeneration; just as an active healthy man sometimes degenerates when he becomes suddenly possessed of a fortune; or as Rome degenerated when possessed of the riches of the ancient world. The habit of parasitism clearly acts upon animal organization in this way. Let the parasitic life once be secured, and away go legs, jaws, eyes, and ears; the active, highly-gifted crab, insect or annelid may become a mere sac, absorbing nourishment and laying eggs."[95]
There could be no more impressive illustration than this of what with entire appropriateness one might call "the physiology of backsliding." We fail to appreciate the meaning of spiritual degeneration or detect the terrible nature of the consequences only because they evade the eye of sense. But could we investigate the spirit as a living organism, or study the soul of the backslider on principles of comparative anatomy, we should have a revelation of the organic effects of sin, even of the mere sin of carelessness as to growth and work, which must revolutionize our ideas of practical religion. There is no room for the doubt even that what goes on in the body does not with equal certainty take place in the spirit under the corresponding conditions.
The penalty of backsliding is not something unreal and vague, some unknown quantity which may be measured out to us disproportionately, or which perchance, since God is good, we may altogether evade. The consequences are already marked within the structure of the soul. So to speak, they are physiological. The thing affected by our indifference or by our indulgence is not the book of final judgment but the present fabric of the soul. The punishment of degeneration is simply degeneration--the loss of functions, the decay of organs, the atrophy of the spiritual nature. It is well known that the recovery of the backslider is one of the hardest problems in spiritual work. To reinvigorate an old organ seems more difficult and hopeless than to develop a new one; and the backslider's terrible lot is to have to retrace with enfeebled feet each step of the way along which he strayed; to make up inch by inch the lee-way he has lost, carrying with him a dead-weight of acquired reluctance, and scarce knowing whether to be stimulated or discouraged by the oppressive memory of the previous fall.
We are not, however, to discuss at present the physiology of backsliding. Nor need we point out at greater length that parasitism is always and indissolubly accompanied by degeneration. We wish rather to examine one or two leading tendencies of the modern religious life which directly or indirectly induce the parasitic habit and bring upon thousands of unsuspecting victims such secret and appalling penalties as have been named.
Two main causes are known to the biologist as tending to induce the parasitic habit. These are, first, the temptation to secure safety without the vital exercise of faculties, and, second, the disposition to find food without earning it. The first, which we have formally considered, is probably the preliminary stage in most cases. The animal, seeking shelter, finds unexpectedly that it can also thereby gain a certain measure of food. Compelled in the first instance, perhaps by stress of circumstances, to rob its host of a meal or perish, it gradually acquires the habit of drawing all its supplies from the same source, and thus becomes in time a confirmed parasite. Whatever be its origin, however, it is certain that the main evil of parasitism is connected with the further question of food. Mere safety with Nature is a secondary, though by no means an insignificant, consideration. And while the organism forfeits a part of its organization by any method of evading enemies which demands no personal effort, the most entire degeneration of the whole system follows the neglect or abuse of the functions of nutrition.