or, as Mill more eloquently puts it, "it is necessary to preserve the soil in which they [geniuses] grow. Genius can only breathe freely in an atmosphere of freedom...If from timidity they consent to be forced into one of these moulds [of conformity]...society will be little the better for their genius" (on Liberty, 9). Mill uses the extreme example of genius to illustrate the general principle he has devoted this entire book to; namely, that individual liberty is essential for the progress of a society. In this particular facet of his argument, he uses the archetypal vision of the genius to add a concrete incarnation of what otherwise might be an abstract and abstruse concept. Instead, Mill's view of liberty is rendered strikingly clear by his use of logic...

All of this argument, though, is really just an expansion and explanation of his basic harm principle, still the most succinct yet complete definition of liberty available.
There is a reason that Mill's on Liberty is one of the most referred-to texts in libertarian and anti-libertarian thought. Mill's simple eloquence of language and elegance of thought makes this essay at once incredibly profound and eminently accessible. His basic argument could be summed up in one sentence: "Liberty, the ideal state for human beings, consist of doing what you will without harming others." The remainder of this volume is aimed at demonstrating the truth and benefits of this "harm principle," and through a few basic premises and a careful application of logic, Mill is hugely successful in this aim.