Why it's name is "The science of the Lambs"?

Why it's name is "The science of the Lambs"?Still can't find the answer after watching the movie. In gerneral, it a good movie. It breakthroug the traditional story ruts which thinking much of polt and narrating single angle.it's plot is acctrative, but not boring. You need think together with the chief actress , put yourself in danger as if you are a member of this story.you will feeling curiors , anger , scared, anxious .....however , the one let me the deepest impression is the word "transfer", which has been mentioned several times in the movie.