How does Neil Gaiman use imagery in Stardust?

Imagery:

The wine was streaming and bubbling, and it came to Tristran then-the information surfacing from some long-forgotten fairy tale or piece of children's lore-that a unicorn's horn was proof against...
'Poison?' he whispered, and the unicorn raised its head, and stared into Tristran's eyes, and Tristran knew that it was the truth. His heart was pounding hard in his chest. Around the inn the wind screamed like a witch in her madness."