"Men have wasted away before it, entranced by what they have seen, or been driven mad, not knowing if what it shows is real or even possible." - Albus Dumbledore
The Seven of Cups shows unrealistic wishful thinking, and the disarray that could occur if one lets himself succumb to only his daydreams.
The Mirror of Erised will show anyone who looks into it his heart's deepest desire. However, it is very easy for the weak of will to be trapped by it, always dreaming of that fantasy but never being able to work toward achieving the goal. No one can live on wishful thinking--they must take action if they want to see their dream come true.
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