Let him send no more— / Unless perchance you come to me again (1.5. )
Olivia tells Viola/Cesario that she does not want to hear anything else from the Duke, and then drops a sly hint about her interest in Cesario. She would like to see Cesario again. This line alerts Viola to the dangerous situation she finds herself in, where Olivia is now in love with Cesario. It also shows Olivia being relatively bold for a woman of her time, in openly hinting at her desire.
Methinks I feel this youth’s perfections / With an invisible and subtle stealth / To creep in at mine eyes (1.5.)
Olivia is bit surprised and even distressed at realizing she feels attracted to Cesario, but she also cannot deny the way she is responding to him. The quote is ironic, because while Olivia is surprised to find herself attracted to a man, she is really attracted to another woman pretending to be a man. The beauty she admires in Cesario are really Viola’s feminine features shining through.
I have said too much unto a heart of stone / And laid mine honor too unchary on’t (3.4.)
Olivia laments that Cesario seems unmoved by Olivia’s confession of love, and admits that she is embarrassed to speak so openly about her feelings. For a high-ranking woman like Olivia to openly declare her love would have been considered improper, but Olivia cannot hold back her feelings. Olivia resembles Orsino in that she is impulsive and melodramatic about her feelings. However, she is also aware that by admitting to feeling love and desire, she is risking her honor and reputation.
Plight me the full assurance of your faith / That my most jealous and too doubtful soul / May live at peace (4.3.)
Olivia, mistaking Sebastian for Cesario, is anxious to get married. She explains that she knows things are moving quickly, but that she will not feel at ease with their relationship until the two of them are wed. Marriage was an important contract and source of security at the time; for Olivia, getting married means that her honor will be protected, and that she knows her beloved cannot leave her.
Fear not, Cesario. Take thy fortunes up (5.1.)
Olivia thinks Cesario is afraid of admitting that the two of them have secretly married. Cesario has just denied being married to Olivia, and Olivia, who is mistaking Cesario for Sebastian, thinks Cesario is lying out of fear of what Orsino will do. Olivia indicates that the marriage has elevated her husband from a relatively humble position to a higher social station, and will give him access to greater wealth and power.