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How to Memorize by St. Thomas Aquinas

St. Thomas Aquinas
St. Thomas Aquinas (1225-1274)

In the Summa Theologica, where St. Thomas Aquinas teaches on the virtue of Prudence, he explains that Memory is a part of this virtue. In that place, he explains how one exercises the Memory

“There are four things whereby a man perfects his memory.”

Let’s study and discuss how this knowledge of how a man may perfect his memory may be applied to our studies. Please note that I have written the applications, but St. Thomas write the rules and explanations.

Step 1. Illustrate

First, when a man wishes to remember a thing, he should take some suitable yet somewhat extraordinary illustration of it.


For the extraordinary strikes us more, and so makes a greater and stronger impression on the mind; the mind; and this explains why we remember better what we saw when we were children. Now the reason for the necessity of finding these illustrations or images, is that simple and spiritual impressions easily slip from the mind, unless they be tied as it were to some corporeal image, because human knowledge has a greater hold on sensible objects. For this reason memory is assigned to the sensitive part of the soul.


St. Thomas explains that ideas to be memorized are hard to hold on to the more “spiritual” or abstract they are. By associating the to some sensible thing in the mind, we tie them down and can hold on to them better.

He mentions sight and images, but this also applies to all of the senses. This is why we more easily memorize the words of songs we hear, the names of foods we eat, of flowers we smell, of materials we feel, and so on. Sight, however, is the most power of the senses, so it is the most effective.

Normally, when we wish to memorize something, there are certain key words in the sentence, which we need to emphasize and these should be the source of our illustration. If we paint in our minds an illustration of what is being memorized, it will help us to remember it.

For example, if we have to remember “Man is a creature composed of body and soul, and made to the image and likeness of God.”, the important words are set in bold print.

We can imagine God as a great fire, making a man out of clay and putting some of His fire within the clay body. If we think of this image we can more easily memorize the sentence.

Step 2. Order

Secondly, whatever a man wishes to retain in his memory he must carefully consider and set in order, so that he may pass easily from one memory to another.


Hence the Philosopher says: “Sometimes a place brings memories back to us: the reason being that we pass quickly from the one to the other.”


In the first step, we talked about identifying the important words of the sentence to be memorized and using them to form an illustration. That gets the image in our mind, but we now need to connect all of those words together so that each part leads into the next. The sentence needs to be carefully arranged in its composition and then we need to memorize it so that all of the parts are tied together.

  1. “Man is a creature.”
  2. “…creature composed…”
  3. “Man is a creature composed…”
  4. “…composed of body and soul…”
  5. “…soul made…”
  6. “Man is a creature composed of body and soul made…”
  7. “…made in the image…
  8. “Man is a creature composed of body and soul made in the image…”
  9. “…image and likeness…”
  10. “Man is a creature composed of body and soul made in the image and likeness of God.”

In the example above, you can see how we memorized each key phrase, but also the connecting terms that lead us from one phrase to the next.

3. Will

Thirdly, we must be anxious and earnest about the things we wish to remember.


The more a thing is impressed on the mind, the less it is liable to slip out of it. Wherefore Tully says in his Rhetoric [*Ad Herenn. de Arte Rhet. iii.] that “anxiety preserves the figures of images entire.”


Here, we have to simply do the work. We have our illustration. We have our memory work ordered and prepared for memorization. Now, we have to drill and drill and drill, to carve this sentence into our minds so that it cannot be erased. We will sense when each phrase is fixed because we will no longer struggle to remember it. Eventually, we will fix the entire sentence in our mind and will be able to repeat it easily and perfectly with no delay.

This is where we prove whether we want it or not.

4. Reflect

Fourthly, we should often reflect on the things we wish to remember.


Hence the Philosopher says (De Memoria i) that “reflection preserves memories,” because as he remarks (De Memoria ii) “custom is a second nature”: wherefore when we reflect on a thing frequently, we quickly call it to mind, through passing from one thing to another by a kind of natural order.


If our knowledge is real and we are constantly building on what we have learned, we will not forget our memorized work because we will constantly be thinking about it and working with it.

Artificial school programs that are not connected with our real lives do not allow for this reflection, because the studies are disconnected and the pursuit of them is not sincere or lasting. They are studied for a grade and then forgotten.

We should (and do) study what we wish to become because this will cause our studies to remain with us, and allow us to constantly revisit them and keep hold of them.

We should answer questions that arise in life not with new opinions or “our own words”, but by reflecting on what we have studied. We should answer using the words we have memorized, which are exact., well-ordered and always with us.

If we are studying what is important and living as we should, this reflection will be natural. Often, when we are unable to retain important knowledge, it’s because we’re not doing what we should, through which it would be remembered. For example, in my talks, you will often hear me quoting Scripture or passages from wise men, but this is not because I memorized them and artificially review them. It’s because I am constantly thinking about them and working with them and they never fall out of my mind.


In this lesson, we have studied how one can perfect his memory, with the direction of one of history’s wisest men, St. Thomas Aquinas. By practicing these methods, we can improve our ability to memorize and, more importantly, to keep hold of the important information we study, that we may make constant and ready use of it throughout life. This, after all, is the benefit of studying.

God bless your studies,
Mr. William C. Michael, Headmaster
Classical Liberal Arts Academy

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