The Lone Star Ranger by Zane Grey

Next morning Duane found that a moody and despondent spell had fastened on him. Wishing to be alone, he went out and walked a trail leading round the river bluff. He thought and thought. After a while he made out that the trouble with him probably was that he could not resign himself to his fate. He abhorred the possibility chance seemed to hold in store for him. He could not believe there was no hope. But what to do appeared beyond his power to tell.

Duane had intelligence and keenness enough to see his peril -- the danger threatening his character as a man, just as much as that which threatened his life. He cared vastly more, he discovered, for what he considered honor and integrity than he did for life. He saw that it was bad for him to be alone. But, it appeared, lonely months and perhaps years inevitably must be his. Another thing puzzled him. In the bright light of day he could not recall the state of mind that was his at twilight or dusk or in the dark night. By day these visitations became to him what they really were -- phantoms of his conscience. He could dismiss the thought of them then. He could scarcely remember or believe that this strange feat of fancy or imagination had troubled him, pained him, made him sleepless and sick.