Every language has a way of talking about seeing, hearing, smelling, tasting and touching. In about a quarter of the world's languages, grammatical evidentials express means of perception (visual, and non-visual) and information source in general. Lexical verbs covering perception and cognitive processes may or may not form a special subclass of verbs. Their meanings vary. In some languages verbs of vision subsume cognitive meanings (knowledge and understanding). In others, cognition is associated with a verb of auditory perception, touch, or smell. Grammatical, and lexical, expression of perception and cognition share a number of features. 'Vision' is not the universally preferred means of perception. In numerous cultures, taboos are associated with forbidden visual experience. Vision may be considered intrusive and aggressive, and linked with access to power. In contrast, 'hearing' and 'listening' are the main avenues for learning, understanding and 'knowing'. The studies presented in this book set out to explore how these meanings and concepts are expressed in languages of Africa, Oceania, and South America. The final section of this chapter offers an overview of the volume.