Peter J. Collings is Morris L. Clothier Emeritus Professor of Physics at Swarthmore College and Adjunct Professor of Physics at the University of Pennsylvania, USA. He is a Fellow of the American Physical Society and past Vice-President of the International Liquid Crystal Society. He is the author of Liquid Crystals: Nature’s Delicate Phase of Matter (Princeton University Press, 1990, 2002) and co-author of the first edition of Introduction to Liquid Crystals: Chemistry and Physics (Taylor & Francis, 1997). John W. Goodby is Emeritus Professor of Materials Chemistry at the University of York, UK. He is a Fellow of the Royal Society and past President of the International Liquid Crystal Society. He is the co-author of Smectic Liquid Crystals: Textures and Structures (Leonard Hill, 1984), Ferroelectric Liquid Crystals: Principles, Properties and Applications (Gordon & Breach 1991), and Senior Editor of the Handbook of Liquid Crystals (Wiley-VCH, 2014).