By my faith the fool has feathered his nest well.

The speaker swears (“By my faith”) and remarks, with irony, that a “fool” has nonetheless managed to “feather his nest”—i.e., secure comfort, profit, or a safe position, often by opportunism rather than merit. The line plays on a common proverbial image: birds lining a nest with feathers to make it warm, transferred to human self-enrichment. Its bite lies in the contrast between the person’s supposed foolishness and the evident success of their self-serving arrangements, implying that social or financial advancement may reward cunning, luck, or unscrupulous behavior even when wisdom is absent.