Possible Clues:

• Curiosity of artist right before thing with unknown
• Wonder when 2, all but its first and second failing
• Uncommon event
• Find it in tracks artist laid down first?
• Poe's autograph, e.g
• Some hope to keep laughing, not an uncommon thing
• I tarry over scarce object
• Blue moon, for instance
• It's unusual, artist showing opulence, but not unknown
• Albino, for one