Yet doth this accident and flood of fortune / 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.