Developing the view that philosophy is acquisition of knowledge also requires answering the question: What is the relation of knowledge to emotions? A widely held view is that, while playing a positive part in the biological role of knowledge, emotions play a negative part in the cultural role of knowledge, but this chapter argues that this view is not valid. Alternatively, the chapter argues that emotions play a positive part both in the biological role of knowledge and in the cultural role of knowledge. In particular, emotions play a positive part in science and mathematics.