This article argues that knowledge is not a passive product of learning that can be possessed, but rather that it represents an active engagement with ideas, arguments and the world in which they reside. This engagement requires a state of 'knowing' -- a complex, integrative, reciprocal process that unites the knower with the to-be-known. Exploring the notion of knowledge, this paper considers the roles of truth and belief in knowledge production, the relationship between knowledge and the disciplines, and knowledge as a social and cultural product. These ideas are contextualized in higher education practice with an example of a course designed to help science and engineering students develop criticality and a sense of 'knowing' about the world. The students are challenged to consider what it requires to turn facts and information into knowledge, and to unite their knowing with their own personal experiences and ideas about the world.