No one thought much of it at first. It was the hot weather, they said, which made him so quiet, and which led him to lie for hours together on a rug which his father spread for him under the lilac bush, unable to play, too weary even to look at pictures, too weak and tired to do anything but watch the swallows flying backwards and forwards, and round and round, as they looked for food for the little birds in the nest. It was the hot weather, they felt sure, which had taken away his appetite, and which had made him look even more thin, and pale, and fragile than he did before.