Final answer:
Lotte may be weeping at the camp fence due to traumas that have stripped her ability to recall happy memories, unlike Gerda who still has such memories. The excerpts from various sources reflect the themes of memory loss, sadness, and isolation, which are relevant to Lotte's experience.
Step-by-step explanation:
The provided excerpts suggest that Lotte is weeping because she has endured traumas that have prevented her from accessing happy memories for comfort, unlike Gerda who may have such memories to draw strength from. In the excerpts, the characters grapple with profound sadness, loss, and isolation. Themes of memory and its loss, as well as the impact of life experiences on an individual's mental state, are prevalent. For instance, the passage that discusses a person having 'drained the whole experience in an instant, and there was left to her only the empty and withered husks of the hours' speaks to how a deeply traumatic event can leave someone unable to recall happier times. Likewise, mentions of a desolate hearth and someone left all alone reinforce the idea of profound isolation, which can contribute to one's inability to recall comforting memories.