For, you see, so many out-of-the-way things had happened lately, that Alice had begun to think that very few things indeed were really impossible.
After several shocks, Alice revises her sense of the possible. The sentence enlarges the world by soft exaggeration—“very few things indeed” closes almost no doors. Hopeful fits because she welcomes the widened horizon. Thematically, transformation starts in the mind: beliefs stretch, then behavior follows. Wonderland becomes a training ground for flexible thinking. Readers feel permission to try odd paths when old rules break. It’s growth as openness, not just size change.