John Stuart Mill’s assertion that liberty involves pursuing one’s desires comes from his influential 1859 essay, "On Liberty," a foundational text in liberal political philosophy. Written with the significant input of his wife, Harriet Taylor Mill, the work explores the crucial balance between individual freedom and societal authority. Mill developed this idea within the context of his "harm principle," arguing that the only legitimate reason for society to interfere with an individual's liberty is to prevent harm to others. He was particularly concerned about the "tyranny of the majority," where prevailing public opinion could stifle individual expression and unconventional ways of life.

The deeper meaning of this statement lies in Mill’s belief that true human flourishing and societal progress depend on individuals being free to develop their unique potential and pursue their own conception of a good life. "Doing what one desires" is not an endorsement of reckless abandon, but rather an emphasis on self-determination and the freedom to make choices, even if those choices seem unconventional to others. Mill believed that allowing individuals this freedom, especially in "self-regarding actions" that primarily affect only themselves, fosters creativity, diverse experiences, and ultimately a more vibrant and adaptable society.

This philosophical cornerstone continues to resonate deeply in discussions about civil liberties and democratic principles today. It underpins arguments for freedom of speech, personal lifestyle choices, and the protection of minority rights against overwhelming societal pressure. Historically, Mill's ideas laid much of the groundwork for modern liberal thought, challenging rigid social norms and advocating for a society where individuals are encouraged to think critically and explore their own paths, so long as they do not infringe upon the equal liberty of others.