John Stuart Mill (1806-1873) was an English philosopher and economist. He wrote one of his most famous essays, "On Liberty", in 1859.

"On Liberty" is the philosophy classic that laid the foundation of modern liberal politics, by applying the concept of utilitarianism to societies and countries, in order to create a working system between authority and liberty.

It was widely read at the time, and in the century and a half since it was published, it has proven to be one of the most influential books of political philosophy of all time.