Explaining the interactions of humans with their environment through the lens of chemistry. Knowledge is limited by experience. The knowledge base can be expanded by travelling to seek new (or applicable) knowledge. There are examples of the transmission of knowledge to Norfolk (and to other places in England) from Europe via the Hanseatic League and from further afield. The knowledge of atoms, structures of molecules and bonding increased gradually. This led to proposals regarding concepts such as tautomerism and to the creation of increasingly sophisticated models. Knowledge is created and assimilated on a personal, institutional and societal level and can be transmitted between entities at each of these levels. There can be unintended and unanticipated consequences of the generation of knowledge and some of these will create fear and misgivings about progress. It is important that chemists (and scientists generally) carry out work that meets a perceived or potential need and has value. Embarking on a programme of work simply to demonstrate that it is possible or to just showcase scientific expertise is often meaningless and counterproductive. It also creates a barrier between science and society and thereby undermines the partnership referred to earlier.