In "Lord Foulgrin's Letters," the character Foulgrin advises Squaltaint that the key to temptation lies in preventing Fletcher from firmly rejecting it. He suggests that if Fletcher never says a clear no, the temptation remains alive, effectively leaving the door open for eventual acceptance. This perspective underscores the idea that wavering on moral choices can lead to eventual downfall.

Foulgrin's counsel emphasizes how indecision can be manipulated, illustrating that any hesitation or uncertainty can be exploited by temptation. The essence of Foulgrin's strategy is to keep individuals dubious, thus making it easier for them to eventually surrender to their desires without realizing the danger they face.