Thou shouldst have looked before thou hadst leapt.—Jonson, Chapman, Marston: Eastward Ho, act v. sc. 1.
Look before you ere you leap.—Butler: Hudibras, pt. ii. c. ii. l. 502.
He that will not when he may,
When he will he shall have nay.
Burton: Anatomy of Melancholy, pt. iii. sec. 2, mem. 5, subs. 5.
He that wold not when he might,
He shall not when he wolda.
The Baffled Knight. Percy: Reliques.
[9:7] All the fatt 's in the fire.—Marston: What You Will. 1607.