A metaphor for being sensitive could be "wearing your heart on your sleeve," implying that one's emotions are easily visible and vulnerable to external influences.
Heart on My Sleeve was created on 2009-04-14.
A 'beating heart' is not a metaphor, but is rather personification.
It is a metaphor.
"Wear your heart on your sleeve" means that you don't hide your emotions. Everyone can see immediately how you feel about something.
No
nowhere
You do this by outwardly showing your emotions.
This idiom is wearing their heart on their sleeve. It means everyone can see how that person feels. Perhaps showing love towards another person.
cold heart
Simile
When he says "wear your heart on your sleeve" he's saying that they would show their emotions more and not conceal their feelings. When he says paper heart he's saying that their heart is very frail like paper