James Clerk Maxwell (1831-1879) was the greatest physicist of the nineteenth century, and although his scientific contribution is now acknowledged to be on a level with those of Newton and Einstein, he has generally not received the acclaim that he deserves. This book goes beyond the life of the man himself to explore five generations of his family and those with whom they were connected, predominantly middle ranking lowland Scots who were interlinked through marriage. At the centre are the Clerks of Penicuik and the Maxwells of Middlebie. These dynastic families and their connections produced several astonishing characters whose stories shed light on the development of Scotland from the political and religious aftermath of the Reformation, through the age of Enlightenment, and into the glory days of the nineteenth century. The Scottish Enlightenment was fuelled by the actions and ideas of several brilliant individuals, many of whom were either among James Clerk Maxwell's direct forebears or within their circle of connections. Their brightest scion was without doubt James himself, but many of the others also made their own distinct impression on Scotland and the wider world.