Answer:
The theme that "Lost Illisions" contains is how children start out young and innocent but inevitably have to face the turht of reality and life. The narrator talks about veils that sheilded her from the actuality of life in her youth, but when she left the comfort and shelter of the veils she realized the true sadness and despair associated with reality. The speaker wants desperately to hide behind the veils that sheilded her in her youth once more.
Explanation:
Plato answer but re-worded. :)