"I fear the man of one book" - What is your attitude towards this thought? A while ago I heard said phrase being interpreted as a warning toward people who only have knowledge from a single source (a single book, the oneself's perspective, a single author, a single teacher, etc.).

Buddhism touches a lot of topic today divided into individual sciences and knowledges of their own. That's why the Dhamma is usually classified as a philosophy, a psychology, a religion, and so on. But in Buddha's time and considering the purpose of the Dhamma, those bounderies where useless and alien to the practice itself. The Buddha used elements from all sorts of areas and knowledges in order to eradicate Dukkha and to reach the other shore.

In modern times, we know a lot more about the working of the brain, about human physiology, about philosophy and science in general, about the development of religions and cultures, and about the world in general. 

With that in mind: should we fear the men of one book? 

Should the ones following the Dhamma know and study these other areas in order to contrast and prove the reality of the Buddha's words? 

Or is it enough with just reading Dhamma books?
If you lean on that second field, do you trust that the Buddha was inerrant and/or that the authors of the Suttas had the Buddha's words transcribed verbatim?

I'm not sure if this kind of questions are appropiated for this site. If not, just ignore it and close it.

EDIT: What motivated this question is that strange vibe that arises when I read discussion where people base their answers and arguments only on suttas and Dhamma books. While that's OK, specially on academic sites, it's pretty weird to me that such an experiential and pragmatic thing as the Dhamma is, is a lot of times covered by a dogmatic and scholar aura, which puts in motion endless debates about the nature of consciousness, the place where kammic seeds are stored, the time it passes before rebirth and that sort of things. But I always end with this question in my head: are people telling about X thing because they have experienced themselves such phenomena, or because the suttas said so, or both?

EDIT 2: Wow! Such good answers! I cannot pick one over another. For these cases, I'd love to choose more than one.
Thanks for those well thought and well put idea!

Thanks for your time and patience!
You can study other fields like science, psychology, philosophy, physiology, culture, other religions etc. That's no conflict with Buddhism.

However, using other fields to validate Buddhism is not the right approach. The reason for this is that other fields have different objectives compared to Buddhism. To compare them would be the same as comparing oranges and apples.

Buddhism has one primary objective - to reduce and end suffering, which basically relates to achieving permanent stable happiness.

The only way to validate Buddhism is to compare its teachings and the effects of its practices (as practised by oneself) against one's own experiences. Does it reduce your suffering? Does it help you reduce your bad habits and improve your harmony with yourself and others? Does it promote an increase in your own happiness and better psychological well-being?

Back to the first point, studying other fields can broaden your understanding of other fields. This has a few benefits.

Firstly, it helps prevent a Buddhist from becoming extreme or ritualistic or overly clinging to rules in his view. This actually is one of the fetters that the stream winner has to eliminate, through seeing the Dhamma clearly.

Secondly, it prevents a Buddhist from becoming disconnected from the "rest of the world". The Buddha wanted his monks to depend on the laity for alms, so that the monks don't become disconnected from the "rest of the world" and also for the laity to interact and learn from the monks.

Thirdly, understanding other fields can help with the validation of Buddhism against one's own experiences, because it can help feed one's insight. Let me use the example of Nobel prize winning physicist Richard Feynman (quoted below from here). Teaching basic physics to students is not required for one dedicated to research, but getting questions and interacting with students help to feed into his insight, so he found it necessary.

So, although Buddhist teachings and practices combined with one's own experience is enough to "research" (i.e. gain insight) into the nature of one's reality in order to end suffering, learning other fields can be helpful in feeding that insight. In this question, I tried to compare the nature of the mind vs. body to software vs. hardware. That doesn't mean mind IS software, but knowledge of the nature of software vs. hardware can feed into the insight into the nature of the reality of mind vs. body.


  When I was at Princeton in the 1940s I could see what happened to
  those great minds at the Institute for Advanced Study, who had been
  specially selected for their tremendous brains and were now given this
  opportunity to sit in this lovely house by the woods there, with no
  classes to teach, with no obligations whatsoever. These poor bastards
  could now sit and think clearly all by themselves, OK? So they don't
  get any ideas for a while: They have every opportunity to do
  something, and they are not getting any ideas. I believe that in a
  situation like this a kind of guilt or depression worms inside of you,
  and you begin to worry about not getting any ideas. And nothing
  happens. Still no ideas come.
  
  Nothing happens because there's not enough real activity and
  challenge: You're not in contact with the experimental guys. You don't
  have to think how to answer questions from the students. Nothing!
  
  In any thinking process there are moments when everything is going
  good and you've got wonderful ideas. Teaching is an interruption, and
  so it's the greatest pain in the neck in the world. And then there are
  the longer period of time when not much is coming to you. You're not
  getting any ideas, and if you're doing nothing at all, it drives you
  nuts! You can't even say "I'm teaching my class."
  
  If you're teaching a class, you can think about the elementary things
  that you know very well. These things are kind of fun and delightful.
  It doesn't do any harm to think them over again. Is there a better way
  to present them? The elementary things are easy to think about; if you
  can't think of a new thought, no harm done; what you thought about it
  before is good enough for the class. If you do think of something new,
  you're rather pleased that you have a new way of looking at it.
  
  The questions of the students are often the source of new research.
  They often ask profound questions that I've thought about at times and
  then given up on, so to speak, for a while. It wouldn't do me any harm
  to think about them again and see if I can go any further now. The
  students may not be able to see the thing I want to answer, or the
  subtleties I want to think about, but they remind me of a problem by
  asking questions in the neighborhood of that problem. It's not so easy
  to remind yourself of these things.
  
  So I find that teaching and the students keep life going, and I would
  never accept any position in which somebody has invented a happy
  situation for me where I don't have to teach. Never.