degradation which I believe to be surely going on, not merely in
these islands, but in every civilised country in the world, in
proportion to its civilisation.

It is still a question whether science has fully discovered those
laws of hereditary health, the disregard of which causes so many
marriages disastrous to generations yet unborn. But much valuable
light has been thrown on this most mysterious and most important
subject during the last few years. That light--and I thank God
for it--is widening and deepening rapidly. And I doubt not that
in a generation or two more, enough will be known to be thrown
into the shape of practical and provable rules; and that, if not a
public opinion, yet at least, what is more useful far, a
widespread private opinion will grow up, especially among educated
women, which will prevent many a tragedy and save many a life.

But, as to the laws of personal health: enough, and more than
enough, is known already, to be applied safely and easily by any
adults, however unlearned, to the preservation not only of their
own health, but of that of their children.

The value of healthy habitations, of personal cleanliness, of pure
air and pure water, of various kinds of food, according as each
tends to make bone, fat, or muscle, provided only--provided only--
that the food be unadulterated; the value of various kinds of
clothing, and physical exercise, of a free and equal development
of the brain power, without undue overstrain in any one direction;
in one word, the method of producing, as far as possible, the
mentem sanam in corpore sano, and the wonderful and blessed
effects of such obedience to those laws of nature, which are