Criticised by educators and methodologists for its typical one-way communication, lectures have nevertheless survived in academia, mainly as a quick, cheap and efficient way of introducing large numbers of students to a particular field of study. In past centuries the diffusion of scientific knowledge via handwritten lecture notes was an essential element of academic life (see, for example, the genesis of Ferdinand de Saussure's Cours de linguistique générale); professors were used to actually reading out from their own notes for exactly that purpose. Today, the use of multimedia presentation software such as Microsoft PowerPoint has changed the very essence of lectures, with listeners, as critics put it, being bombarded with all sorts of unnecessary and confusing visual aid.
"Lectures," said McCrimmon, "are our most flexible art form. Any idea, however slight, can be expanded to fill fifty-five minutes; any idea, however great, can be condensed to that time. And if no ideas are available, there can always be discussion. Discussion is the vacuum that fills a vacuum. If no one comes to your lectures or seminars, you can have a workshop and get colleagues involved. They have to come, and your reputation as an adequately popular teacher is saved." (John Kenneth Galbraith, A Tenured Professor)