[Footnote IV.2: In this brainish apprehension,] Distempered, brainsick mood.
[Footnote IV.3: Where the offender's scourge is weigh'd, But never the offence.] When an offender is popular, the people never consider what his crime was, but they scrutinise his punishment.
[Footnote IV.4: Politick worms] i.e., artful, cunning worms.
[Footnote IV.5: The wind at help,] i.e., ready.
[Footnote IV.6: May'st not coldly set] Set is to value or estimate. "Thou may'st not set little by it, or estimate it lightly."