3 Cannot endure, but needs it must be wracked

needs > of necessity, perforce wracked > wrecked, shipwrecked; ruined

4 On the rough rocks, or on the sandy shallows, 5 While Love it steers, and Fortune rows;

Love > [Cupid; on his blindness, see 304.6:8]

6 Love, my lewd pilot, has a restless mind,

lewd > unlearned; bungling; worthless; sorry, poor; lewd, lascivious

7 And Fortune, boatswain, no assurance knows,

assurance > steadiness, intrepidity

8 But sail without stars, gainst tide and wind:

stars > [benefit of navigation by the stars] gainst > against