It is not difficult to ascertain how this opinion originated. There are a few individuals who are perpetually thinking and talking on this subject, and who would fain comply with appropriate rules, if they knew what they were, and if a certain definite course, pursued a few days only, would change their whole condition, and completely restore a shattered or ruined constitution. But their ignorance of the laws which govern the human frame, both in sickness and in health, and their indisposition to pursue any proposed plan for their improvement long enough to receive much permanent benefit from it, keep them, notwithstanding all they say or do, always deteriorating. Then, on the other hand, there are a few who, in consequence of possessing by nature very strong constitutions, and laboring at some active and peculiarly healthy employment, are able for a few, and perhaps even for many years, to set all the rules of health at defiance. Now, strange as it may seem, these cases, though they are only exceptions (and those more apparent than real) to the general rule, are always dwelt upon, by those who are determined to live as they please, and to put no restraint either upon themselves or their appetites. For nothing can be plainer--so it seems to me--than that, taking mankind by families, or what is still better, by larger portions, they are most free from pain and disease, as well as most healthy and happy, who pay the most attention to the laws of human health, that is, those laws or rules by whose observance alone, that health can be certainly and permanently secured. But these families and communities are most healthy and happy, not because they live in a proper manner, by fits and starts, but because they have, from some cause or other, adopted and persevered in HABITS which, compared with the habits of other families, or other communities, are preferable; that is, more in obedience to the laws which govern the human constitution. Not that even _they_ are "without sin" or error on this subject--gross error too--but because their errors are fewer or less destructive than those of their neighbors. Now is it possible that any intelligent father or mother of a family, whose diet, clothing, exercise, &c. are thus comparatively well regulated, would derive no benefit from the perusal of works which treat candidly, rationally, and dispassionately, on these points? Is there a mother in the community who is so destitute of reason and common sense as not to desire the light of a broader experience in regard to the tendency of things than she has had, or possibly can have, in her own family? Is there one who will not be aided by understanding not only that a certain thing or course is better than another, but also WHY it is so?