The ultimate good desired is ...

The ultimate good desired is better reached by free trade in ideas [and] the best test of truth is the power of the thought to get itself accepted in the competition of the market.
The ultimate good desired is better reached by free trade in ideas [and] the best test of truth is the power of the thought to get itself accepted in the competition of the market.
 Oliver Wendell Holmes, Jr.

More phrases

All the great things are simple, and many can be expressed in a single word: freedom, justice, honor, duty, mercy, hope.
I know but one freedom and that is the freedom of the mind.
 Antoine de Saint-Exupéry
Freedom is not worth having if it does not connote freedom to err.
The amount of happiness that you have depends on the amount of freedom you have in your heart.
 Thích Nhất Hạnh
Without freedom of thought, there can be no such thing as wisdom - and no such thing as public liberty without freedom of speech.

Quotes from the same author

What I wouldn't give to be seventy again!
 Oliver Wendell Holmes, Jr.
Many ideas grow better when transplanted into another mind than in the one where they sprung up.
 Oliver Wendell Holmes, Jr.
Be willing to commit yourself to a course, perhaps a long and hard one, without being able to foresee exactly where you will come out.
 Oliver Wendell Holmes, Jr.
With all humility, I think, "Whatsoever thy hand findeth to do, do it with thy might." Infinitely more important than the vain attempt to love one's neighbor as one's self. If you want to hit a bird on the wing you must have all your will in focus, you must not be thinking about yourself, and equally, you must not be thinking about your neighbor; you must be living with your eye on that bird. Every achievement is a bird on the wing.
 Oliver Wendell Holmes, Jr.
Science is the topography of ignorance. From a few elevated points we triangulate vast spaces, inclosing infinite unknown details. We cast the lead, and draw up a little sand from abysses we may never reach with our dredges.
 Oliver Wendell Holmes, Jr.