Rinaldo Enchanted by Armida is a scene from the poem Jerusalem Liberated by Torquato Tasso.  

This is the part where the witch Armida allures good ol’ Christian Crusader Rinaldo away from his mission to “free” Jerusalem from the Muslims.  In other words, some racist guy blames a pretty lady for his uncontrollable libido and uses that as an excuse to ditch his friends.  In the poem, his friends get pissed at him for ditching them (check that out in Armida Abandoned by Rinaldo), but personally I don’t blame Rinaldo. Armida has that whole Glinda the Good Witch vibe going on with her blond hair and cloud-chariot, so of course he’s going to diverge off his path in favor of the yellow brick road in the hopes that he can tap heels with the enchanting sorceress.

This is the first in a series of four paintings depicting scenes in the poem.  Supposedly, this is the stanza on which the painting is based:
... but when she fixed her eyes upon the boy 
and saw how he was breathing peacefully 
and round his pretty eyes a kind of joy 
though they were shut—and how sweet would they be 
when opened—she paused in doubt, then sat nearby, 
and felt her anger melt away as she 
beheld him. Like Narcissus at the pool 
she hung upon his lovely face. 
(XIV, 66)

This stanza basically says that she saw him sleeping and thinks he’s cute and probably has dreamy eyes and she can’t look away because she is so infatuated.  (By the way, she was originally supposed to kill him.)  The clear interpretation would be that she conivingly deceived this poor young man into following her.  Ugh, so over Giovanni Battista Tiepolo’s meninist ideals