i've got a question for anyone who can answer..
i was just flicking through my book again, and came to the chapter on snapes memories "the prince's tale"
i don't understand why he sends his patronus out the window? is it to prove he loved Lily because she too cast a doe as her patronus?
anyway to save everyone looking it up, this is what it says before and after it happens..
(the conversation is between snape 'S' and Dumbeldore 'd')
S: I have spied for you and lied for you, put myself in mortal danger for you. Everything was supposed to be to keep Lily Potter's son safe. Now you tell me you have been raising him like a pig for slaughter. -
D: But this is touching Severus, Have you grown to care for the boy, after all?
S: For him? snape shouted, 'Expecto Patronum!"
From the tip of his wand burst the silver doe: she landed on the office floor, bounded once across the office and soared out of the window. Dumbeldore watched her fly away and as her silvery glow faded he turned back to snape, and his eyes were full of tears.
D: After all this time?
S: Always
And the scene shifted, now Harry saw snape talking to the portrait of dumbeldore behind his desk. (Explains about telling death eaters time of harrys departure)

it could be simple but i have confused myself!