I was looking at a lime or linden tree last autumn, when the sun was shining brightly, and ere the leaves had commenced to turn from green to yellow. All know the graceful and beautiful linden tree, with its wealth of heart-shaped leaves, so close and thick that if a man climbs but half-way up, he is hidden in a cloudland of verdure, and might consider himself a hundred miles from the earth for all he can see of it. And the linden is a spreading tree, its lower branches stretch far outwards, and their tips almost touch the ground, so that once beneath it you are in a kind of fairy alcove or bower, into which even rain cannot find its way. The tree I was looking at was covered with myriads of its strange, wee flowers, the perfume from which had attracted bees in countless thousands. As I stood beneath its shade I was delighted with the fragrance of the wee flowerets, and charmed with the drowsy music of the little artisans, that were so busy gathering honey therefrom—the sweetest and best honey in the world, by the way; but I could not help wondering when I thought of the tens of millions of seeds, which, in a few weeks, would be scattered broadcast upon the earth, not one of which from this particular tree I have ever known to take root and grow. And why not? Listen, because the answer to the question has a bearing upon the subject I have under consideration. The reason why the seeds do not germinate, lies in the fact that the ground on which they fall resists their efforts to take root and grow. As the air is full after a time of the seeds of the linden tree, when the south wind blows, and, as the earth beneath is bedded with them, so, when the chill, cold breezes of spring are blowing, is the sky filled with seeds of illness, which fall on the lungs of those breathing them, and it depends upon the state of one’s blood and constitution, whether those seeds shall take root and develop coughs and colds, and aches and pains and rheums of every kind, or be repelled and do nought of harm. From this we may learn a lesson. For it is strange but true enough, that so great is the struggle for existence in this world—I do not mean among human beings, but among the living though invisible germs which—everywhere and at all times surround us in clouds, that no sooner does the health of anyone of the higher forms of animal life fall below par, than it is attacked by these, and if the weakness is extreme he falls a victim, and severe illness, that may even end fatally, is the result.