'To measure is to know' is a frequently heard saying. Measuring is as old as humanity itself. It's a subject we've struggled with since we learned to count on our fingers, and it continues to amaze the brightest minds in modern science. And why do people want to measure and quantify the world around them? In this 3-part BBC series, Professor Marcus du Sautoy examines the history and development of seven quantities: time, length, mass, luminosity, current, temperature and amount of matter. The research leads to important places and scientists and along the way the influence of measurement on our civilization becomes clearer.