When love once pleas admission to our hearts,
(In spite of all the virtue we can boast),
The woman that deliberates is lost.

Act IV, scene i. The last line has often been misreported as "He who hesitates is lost", a sentiment inspired by it but not penned by Addison. See Paul F. Boller, Jr., and John George, They Never Said It: A Book of Fake Quotes, Misquotes, & Misleading Attributions (1989), p. 3

"When love once pleads admission to our hearts..."