Do you remember that old saying that you are only using 10% of your brain? Occasionally, you still see people repeat it. It’s a myth, largely promoted by some very old neuroscience data when we did not know what certain parts of the brain did. It is also based on a misunderstanding of what psychologists have long believed about human capacity. For example, over a century ago William James famously stated that “We are making use of only a small part of our possible mental and physical resources” (James, 1907, p. 3).

I thoroughly agree with James, and I suspect you do too. When we learn how to do better in life, we can often look backwards and see that the barriers to our growth were not as solid as they appeared at the time. We just didn’t use all of our resources. So let me show you how true this is in the world of thought. I want to convince you that you have vastly more cognitive capacity than you ever deploy. And if it’s true, perhaps we can turn our attention to becoming more effective and creative by beginning to use a bit more of that capacity.

Here is the question I want you to take seriously: How many different things could you possibly think, given everything you now know? Said more simply, how many thoughts are in your head?

We will return to this question in a moment, but before we do, I have another one for you:

How is a cell phone the father of scissors? 

Ponder that odd question and don’t proceed until you come up with a few really good answers. Don’t worry – after a few seconds, answers will start to flow.

How is a cell phone the father of scissors? Well …

  • Perhaps you could use your cell phone to design the scissors.
  • Perhaps you could melt down your cell phone and use some of the plastic or metal it contains for parts of the scissors. 
  • Perhaps you could use your cell phone to map the route to a place where you could make scissors.
  • Perhaps you could go to Amazon on your phone and order a pair of scissors.

It’s pretty clear we could go on for a long time before everyone got tired of this game.

I’ve played it with thousands of people in workshops and talks and no matter which words or objects I pick (in this case, I just picked two objects that were sitting in front of me on my desk), and no matter which relation I choose (comparisons, similarity, differences, causality, and so on) there is always a reasonably apt answer that is seemingly non-arbitrary: it’s seemingly “really” in the objects or events themselves.

That has to be an illusion of mind. It simply can’t be that everything is related to everything else in every possible way, really and truly. But our minds can always come up with an answer.

I spent a few minutes on the internet and found more than 1,000 relational words or phrases like “is the father of.” I was just scratching the surface. Every emotional word can be made into a comparison (e.g., angrier than; happier than, etc.) as can every physical feature (e.g., taller than; bigger than, etc.). But let’s be conservative and say 1,000.

And a recent study in Frontiers of Psychology found that the average 20-year-old American knew about 46,000 words, word variants, or distinctly meaningful word phrases (what are called “lemmas”) and 60 year old’s edged that up another 6,000 or so over their lifetime. Let’s cut that range down the middle and say 49,000 words, word variants, or distinctly meaningful word phrases are likely in your head.

Now consider the fact that right now you probably remember or could construct hundreds of examples of every concrete one of those. Take the word “walk”. Remember Monty Python’s Ministry of Silly Walks? I’d bet you could imagine a few hundred different ways to walk right now if you pushed yourself. Types, sizes, and colors of scissors? Hundreds and hundreds without breathing hard. Same with cell phones. 

Let’s assign a tiny number to this part, just to be ultra conservative. Let’s say you can imagine or remember 150 examples of all concrete words in your head.

It turns out that you could give examples like that for most of the words or word phrases you know. Books like The Longman Grammar of Spoken and Written English suggest that at least half of the words you know are like that, so let’s just cut the 49,000 “lemmas” in half and assume that 24,500 of them you could give examples of  … we will set aside the others for now.

But note also that everyone of those 24,500 events and these 150 examples can be broken into parts. They have features and qualities. Again, let’s not be greedy. We will suppose each word that is concrete enough to give examples has a mere 25 different features or qualities of any kind. For example, “walking” could be on two legs or 100. Scissor can be large or small; sharp or dull.

If 24,500 things each had 25 features of any kind, and you could give 150 examples of each word or feature, and each word or feature could be related to each other word or feature a thousand different ways, how many specific relations could there be in your head just of those events? 

The answer is just under 92 trillion.

This is a highly conservative estimate of the mental relations you could derive if you worked on it. So, how many different thoughts could you construct from that? You probably learned in elementary school that a sentence expresses a complete thought. So how many sentences could you construct from those 92 trillion derived relations?

Sentences vary by context and topic. Most sentences in most types of writing are 15 to 20 words long, while scientific writing is on average a bit longer – in psychology it’s about 25 words long. Since we are asking how many thoughts are possible, let’s go with 25.

But since we are talking about derived relations and it takes a minimum of three words to express a relation (the two events that are related and the relation) let’s divide that sentence length by three – and then round down. I know it’s crude and ultra conservative, but this would allow us to ask how many different sequences of 92 trillion relations are possible if the sequence could vary from 1 to 8 instances where the specific sequence matters, and you can repeat yourself (I didn’t say the thoughts would be interesting!).

That metric gives you a workable but quite conservative final answer. You have 4.617 * 10^61 thoughts at least potentially in your head. 

Now how big of a number is that? I could say it in words, but it won’t help you (when is the last time you use words like “decillion” of “nonillion”?). Instead, let’s use a metaphor.

Suppose every living human being on the planet today could live an infinitely long life and every person were to begin counting all of the grains of sand on Earth at the rate of 1 second per grain, 24 hours a day 7 days a week. There are a bit over 31 ½ million seconds in a year and about 7.9 billion human beings so all of humanity could count a bit less than 248.63 trillion grains of sand every year. We’d run out of all 7.5 quintillion grains of sands on earth every 30 million years or so … but we can just pour them all back and keep counting.

So, when will we get to stop counting if every grain of sand is one of your possible thoughts? 

Ah, well, we’d better get busy. 

At the rate of 248.63 trillion a year we could all count to 4.617 * 10^61 in 1.85684291 * 10^47 years. Said in words that’s a bit less that one octillion, eight hundred fifty-six septillion, eight hundred forty-three sextillion years. Mind you, the universe is only about 13.8 billion years old, so unfortunately we’d need to increase the age of the universe a bit over 134 quintillion times just to finish the job on your head alone.

Whew! We’d be tired!

You might as well say it this way: in principle your capacity for thought is infinite.

I have just two more of the four sextillion thoughts I’ve been allotted to express. 

If you are like me, a huge portion of your thoughts are basically useless to you, so we’d all better figure out a way to take what is useful and leave the rest. Second, your mind grooves your thinking into ruts. If you feel stuck and see no way out (ain’t that familiar?) or if you are finding yourself yet again repeating the same error in your relationships or your mental or physical health (ain’t that like you?)  … see if you can open yourself up to a greater sense of possibility. Try something more truly new and different that originates from a different and rarely visited part of you – then keep your eyes wide for how it works. My blog is all about these things for a reason. We are the social primates who invented this wonderful cognitive tool that now threatens to engulf us.

Healthy variability is our ally – rigidity is not. You may see no alternatives right now, but have faith in yourself and your place in this universe. Remember there are nearly an infinite number of possible thoughts you have never even thought, never mind explored. Together, let’s find a way to use that capacity for the good of us all.


James, W. (1907). The energies of men. The Philosophical Review, 16(1), 1-20. Doi: 10.2307/2177575.