My stars shine darkly over me (2.1.)
Sebastian explains why he doesn’t want Antonio to accompany him. Sebastian says that he seems to be cursed with bad luck: the shipwreck and the loss of his sister could be part of a larger pattern of bad omens. Since Sebastian is fond of Antonio, he would not want his friend to be affected by his own bad luck. The line ironically foreshadows what will actually happen to Sebastian, in that he will be blessed with lots of good luck due to being mistaken for Cesario by Olivia.
If it be thus to dream, still let me sleep! (4.1.)
Sebastian marvels at the strangely warm and tender treatment he receives from Olivia. He does not know that she has mistaken him for Cesario, and is confused as to why a beautiful and wealthy woman is being so nice to him. Sebastian wants this strange state to continue for as long as possible so that he can enjoy Olivia’s attentions, and he expresses his hope that nothing will change.
Yet doth this accident and flood of fortune / So far exceed all instance, all discourse / That I am ready to distrust mine eyes (4.3.)
Sebastian tries to make sense of the way Olivia is treating him. He cannot understand why she is lavishing him with so much love and luxury, and he is both delighted and worried about his situation. The reversal of his fortune is so striking that he wonders if he might be going crazy and imagining everything. Sebastian’s confusion is particularly intense because he had started off by thinking of himself as doomed or cursed, and now everything seems to be working in his favor.