Adventures come to the adventurous, and mysterious things fall in the way of those who, with wonder and imagination, are on the watch for them; but the majority of people go past the doors that are half ajar, thinking them closed, and fail to notice the faint stirrings of the great curtain that hangs ever in the form of appearances between them and the world of causes behind. For only to the few whose inner senses have been quickened, perchance by some strange suffering in the depths, or by a natural temperament bequeathed from a remote past, comes the knowledge, not too welcome, that this greater world lies ever at their elbow, and that any moment a chance combination of moods and forces may invite them to cross the shifting frontier.