It is another mark of leprosy that sooner or later it _affects the whole man_; and in this, again, appears the sad fitness of the disease to stand as a symbol of sin. For sin is not a partial disorder, affecting only one class of faculties, or one part of our nature. It disorders the judgment; it obscures our moral perceptions; it either perverts the affections, or unduly stimulates them in one direction, while it deadens them in another; it hardens and quickens the will for evil, while it paralyses its power for the volition of that which is holy. And not only the Holy Scripture, but observation itself, teaches us that sin, in many cases, also affects the body of man, weakening its powers, and bringing in, by an inexorable law, pain, disease, and death. Sooner or later, then, sin affects the whole man. And for that reason, again, is leprosy set forth as its pre-eminent symbol.
It is another remarkable feature of the disease that, as it progresses from bad to worse, the victim becomes more and more _insensible_. This numbness or insensibility of the spots affected--in one most common variety at least--is a constant feature. In some cases it becomes so extreme that a knife may be thrust into the affected limb, or the diseased flesh may be burnt with fire, and yet the leper feels no pain. Nor is the insensibility confined to the body, but, as the leprosy extends, the mind is affected in an analogous manner. A recent writer says: "Though a mass of bodily corruption, at last unable to leave his bed, the leper seems happy and contented with his sad condition." Is anything more characteristic than this of the malady of sin? The sin which, when first committed, costs a keen pang, afterward, when frequently repeated, hurts not the conscience at all. Judgments and mercies, which in earlier life affected one with profound emotion, in later life leave the impenitent sinner as unmoved as they found him. Hence we all recognise the fitness of the common expression, "a seared conscience," as also of the Apostle's description of advanced sinners as men who are "past feeling" (Eph. iv. 19). Of this moral insensibility which sin produces, then, we are impressively reminded when the Holy Spirit in the Word holds before us leprosy as a type of sin.
Another element of the solemn fitness of the type is found in the persistently _hereditary_ nature of leprosy. It may indeed sometimes arise of itself, even as did sin in the case of certain of the holy angels, and with our first parents; but when once it is introduced, in the case of any person, the terrible infection descends with unfailing certainty to all his descendants; and while, by suitable hygiene, it is possible to alleviate its violence, and retard its development, it is not possible to escape the terrible inheritance. Is anything more uniformly characteristic of sin? We may raise no end of metaphysical difficulties about the matter, and put unanswerable questions about freedom and responsibility; but there is no denying the hard fact that since sin first entered the race, in our first parents, not a child of man, of human father begotten, has escaped the taint. If various external influences, as in the case of leprosy, may, in some instances, modify its manifestations, yet no individual, in any class or condition of mankind, escapes the taint. The most cultivated and the most barbarous alike, come into the world so constituted that, quite antecedent to any act of free choice on their part, we know that it is not more certain that they will eat than that, when they begin to exercise freedom, they will, each and every one, use their moral freedom wrongly,--in a word, will sin. No doubt, then, when such prominence is given to leprosy among diseases, in the Mosaic symbolism and elsewhere, it is with intent, among other truths, to keep before the mind this very solemn and awful fact with regard to the sin which it so fitly symbolises.