I’ve written before about Henry Hazlitt. He was a brilliant thinker and writer. He was just 21 years old when he wrote a book called Thinking as a Science.

When the book was republished, 53 years later, he wrote an epilogue called The Art of Thinking.

It is a fascinating epilogue, full of brilliant insights and well worth the 15-20 minutes required to read it. Here are a few excerpts:

A man with a scant vocabulary will almost cer­tainly be a weak thinker. The richer and more copious one’s vocabulary and the greater one’s awareness of fine distinctions and subtle nuances of meaning, the more fertile and precise is likely to be one’s thinking. Knowledge of things and knowledge of the words for them grow together. If you do not know the words, you can hardly know the thing.

There are still further corol­laries to be drawn from the inex­tricable interdependence of thought and language. He who seeks to be a clear and precise thinker must also seek to be a clear and precise writer. Good writing is the twin of good think­ing. He who would learn to think should learn to write.

One incidental advantage of the habit of writing out one’s ideas is that it promotes concentration as almost no other practice does. As one who has written daily news­paper editorials or weekly maga­zine columns for many years, I can testify that nothing forces one to pull one’s thoughts together more than deciding on a topic, sit­ting before the typewriter, feeding in a clean sheet of paper, and then trying to frame one’s exact theme, title, and opening paragraph.

A question akin to this, which my chapter would raise, is “What is the problem?” Our modern so­cial reformers are constantly pre­occupied, for example, with the problem of poverty. But poverty is the original condition of man, from which he has sought to es­cape by the sweat of his brow, by work, production, and saving. It was when Adam Smith asked him­self not what causes the poverty but what causes the wealth of na­tions that real progress on the problem began to be made. For centuries, in the same way, doc­tors took health for granted and assumed that the only problem is what causes disease. It was not until surgeons tried to transplant kidneys, hearts, and other organs that they became acutely troubled by the problem of what causes im­munity. There is always the pos­sibility of learning more by ask­ing ourselves the opposite ques­tion.

My new book would contain a chapter on “The Dilemma of Spe­cialization.” The dilemma is this. In the modern world knowledge has been growing so fast and so enormously, in almost every field, that the probabilities are immense­ly against anybody, no matter how innately clever, being able to make a contribution in any one field unless he devotes all his time to it for years. If he tries to be the Rounded Universal Man, like Leonardo da Vinci, or to take all knowledge for his province, like Francis Bacon, he is most likely to become a mere dilettante and dabbler. But if he becomes too specialized, he is apt to become narrow and lopsided, ignorant on every subject but his own, and perhaps dull and sterile even on that because he lacks perspective and vision and has missed the cross-fertilization of ideas that can come from knowing something of other subjects. I do not know the way out of this dilemma, or the exact com­promise, but I hope to find it by the time I write my new book.

If I may be permitted a per­sonal note, it seems to me, looking back, that the hours of purest happiness in my own youth were spent in just this way. I would avidly sample one book after an­other, and when the bell rang, and the library closed for the night, and I was forced to leave, I would leave in a state of mental intoxi­cation, with my new-found knowl­edge and ideas whirling in my head. I would speculate eagerly on what solutions the authors I had read had come to in the passages I hadn’t had time to finish. I think now that these unpremedi­tated efforts to anticipate an au­thor’s conclusions stimulated my thinking far more than any con­tinuous uninterrupted reading would have done. In fact, when I came back to one of these same books the next evening, I most often felt let down. The night be­fore, the author had seemed on the verge of some marvelous breakthrough, opening new vistas to the soul, and now he seemed to fizzle out in a truism.