This is one book that is unique in structure — a collection of ideas noted on index cards over 4 decades.Acclaimed mathematician Lloyd N Trefethen, Professor of Numerical Analysis at Oxford University, has created an intellectual diary, marking the development of his interests and ideas, from his teenage years to the present. These thoughts signposts, directing us through a mind that applies the same scientific discipline and rigor in everyday life as needed for success in science and academia; informative and entertaining, Professor Trefethen's Index Cards is a collage of observations of rare clarity, in subjects ranging from astronomy to family life, and from music to politics.The book will be of interest not only to scientists and mathematicians, the general public interested in discerning how a scientific outlook informs the way we see broader issues in the societies we live in as well.