Douglas Brown in his book Principles of Language Learning...

Douglas Brown in his book Principles of Language Learning and Teaching says that: " The Input Hypothesis, a major offshoot of Krashen's Monitor Model, claims that an important "condition for language acquisition to occur is that the acquirer understand (via hearing or reading) input language that contains structure 'a bit beyond' his or her current level of competence (1981a:100). (...) An important part of the Input Hypothesis is Krashen's recommendation that speaking not be taught directly or very soon in the language classroom. Speech will "emerge" once the acquirer has built up enough comprehensible input. Krashen further claims that the best acquisition will occur in environments where anxiety is low and defensiveness is absent". (p.280) We can infer that: