One morning in the late summer, while walking in the fields at my home in South America, I noticed a few purple martins, large, beautiful swallows common in that region, engaged, at a considerable height, in the aerial exercises in which they pass so much of their time each day. By and by, one of the birds separated itself from the others, and, circling slowly downward, finally alighted on the ground not far from me. I walked on: but the action of the bird had struck me as unusual and strange, and before going far, I turned and walked back to the spot where it continued sitting on the ground, quite motionless. It made no movement when I approached to within four yards of it; and after I had stood still at that distance for a minute or so, attentively regarding it, I saw it put out one wing and turn over on its side. I at once took it up in my hand, and found that it was already quite dead. It was a large example of its species, and its size, together with a something of dimness in the glossy purple colour of the upper plumage, seemed to show that it was an old bird. But it was uninjured, and when I dissected it no trace of disease was discernible. I concluded that it was an old bird that had died solely from natural failure of the life-energy. But how wonderful, how almost incredible, that the healthy vigour and joy of life should have continued in this individual bird down to within so short a period of the end; that it should have been not only strong enough to find its food, but to rush and wheel about for long intervals in purely sportive exercises, when the brief twilight of decline and final extinction were so near! It becomes credible--we can even believe that most of the individuals that cease to exist only when the vital fire has burnt itself out, fall on death in this swift, easy manner--when we recall the fact that even in the life-history of men such a thing is not unknown. Probably there is not one among my readers who will not be able to recall some such incident in his own circle--the case of someone who lived, perhaps, long past the term usually allotted to man, and who finally passed away without a struggle, without a pang, so that those who were with him found it hard to believe that the spirit had indeed gone. In such cases, the subject has invariably been healthy, although it is hard to believe that, in the conditions we exist in, any man can have the perfect health that all wild creatures enjoy. X