“Why don’t it move?” she asked herself.

As she put the question the log did move, borne away by the full current.  Mamie, followed by the dog, ran after it, with her eyes aflame with excitement.  Dennis barked, divining something uncanny, eager to distract the mind of his mistress from what seemed to be engrossing it.  Still she ran on, with her eyes upon the log.  The dog knew that she must stop in a moment, that no one could pass the falls unless they went over them.  Did he divine also that she meant to go over them—­that at last, with her poor, imperfect vision, she had seen that way out of captivity?

She reached the point where farther advance was impossible.  To her right rose a solid wall of stone; opposite rose its twin; between the two the river rushed tumultuously, tossing the great logs hither and thither as if they were spilikins.

Mamie watched her own log.  After its goadings it kept a truer course than most of its fellows.  But she had outstripped it.  Standing upon the edge of the precipice, feeling the cold spray upon her face, hearing the maddening roar of the monster below, less to be feared than that other monster from whom she realised that she had escaped, she waited for the final plunge....

What was passing in her mind at this supreme moment?  We may well believe that she saw clearly the past through the mists which obscured the future.  Always she had been a log at the mercy of a drunken father.  Her mother had died in giving birth to her, but she knew vaguely that this mother was a Church member.  She did not know—­and, knowing, could never have understood—­that from her she had inherited a conscience—­or shall we call it an ineradicable instinct?—­which constrained her to turn aside, shuddering, from certain temptations, to obey, without reasoning, certain ethical laws, solemnly expounded to her by a Calvinistic grandmother.  But Nature had been too much for her.  Even as she had turned instinctively and with horror from the breaking of a commandment, so also she had selected the mate who possessed in excess the physical qualities so conspicuously lacking in her.  She had fallen a victim, and a reluctant victim, to the law of compensation.  When Tom Barker held up his finger and whistled, she crawled to him.

The log, slightly rolling, as if intoxicated, neared the brink of the falls.  And then it stopped again, where the river was narrowest and the current strongest.  No log had stopped in this place before; Mamie saw that it was caught by a small rock, and held fast by the other logs behind it.

“It won’t go over,” she murmured.

Within a minute a terrific jam impended.  Across the river Tom was swearing horribly; and between husband and wife rose a filmy cloud of spray upon which were imprinted the mysterious colours of the rainbow, which, long ago, Mamie had been taught to regard as the most wonderful symbol in the world—­God’s promise that in the end good should triumph over evil.