Did Thomas Aquinas Fear the Man of One Book?

A member of the New Saint Thomas Institute recently asked a good question about Saint Thomas Aquinas:

aquinasDear Taylor,
I am truly fascinated by Saint Thomas aquinas’ comment Beware the man of one book.
I can interpret that two ways and I was wondering if you had the original italian, because the word ‘un’ in Italian can mean one book or it can mean a book, and this would help better interpret the meaning.
If it means one book, then it can mean that a man who writes only one book could be limited in his views.
It can also mean that the writer of one book has put a lot of thought and study into writing and therefore he is a thinker and therefore, a person to be reckoned with or an authority on a subject.
On the other hand, to beware of the man who writes A book could mean any book (indefinite article.) which can then mean that he thinks he is an expert and may not be.
So I would love to know the original Italian and context for nothing more than curiosity.


Dear Catherine,

You have some amazing analysis of this quote! I’ve never thought so much about it!

Fortunately for us, Thomas didn’t usually write in Italian! Let’s get into the Latin, which makes it very clear.

We don’t know if Thomas Aquinas really said this (it’s not in his Works as far as I’ve read), but in Latin the received Thomistic proverb is: “Hominem unius libri timeo.” I fear the man of a single book.

Here unius means one and only one. In a medieval context it would refer to a man who has only studied one book. Probably not a man who has written only one book.

So Saint Thomas Aquinas, if he really said it, is communicating that he fears “scholars” who only have a single speciality and not a breath of knowledge (as did his master Saint Albert the Great).

As we show in the New Saint Thomas Institute, Saint Thomas Aquinas was a master of:

  1. Old Testament
  2. New Testament
  3. Aristotle
  4. Boethius
  5. Augustine
  6. Dionysius the Areopagite
  7. Eastern Church Fathers
  8. Science and Astronomy (for his time)
  9. Practical sermons and preaching

Thomas was hardly a man of one book or one speciality. I hope that helps. Thanks for the question!


PS: A few “back to school” slots will be opening up on Monday Aug 17 2015 for those that want to study with us at the New Saint Thomas Institute (NSTI). Please join the NSTI waiting list in order to hold a reservation.

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