There is a very interesting revelation about human’s cognitive ability to focus. It can be a thought, a sight or even a sound, but that revelation is that we can only focus on one moment at a time or small view at a time, where the peripheral is obscured, out of focus and even invisible.
There have been very interesting studies on human sight, on how narrow of a focus we can clearly see through the input organ. They say it is only a 2% of highly focus, were we can see fine details, and less than 20% of peripheral focus for even color recognition. Even when tracking eye moments following someone reading a text on a page, the focus is only one word, to even partial pieces of the word at a time, depending on length. As we read across any page, we can only cognitively focus on one word at a time and everything else is just blurred out.
The other interesting revelation about how narrow of a focus we can give, there is also the concept of time. That any thought in our head or any focus attention is only given to one thing, and nothing more. We cannot think of two or more things at the same time. Thoughts and focus can change as time goes on, but in one moment, that one thought, that one sight, that single word on a page you are reading, it is the only thought you can give. You think about something else, the thought is removed and replaced with that other thought.
They even say that post rationalization, (thoughts about why you did something, like something, hated something after the fact), is, completely made up on the fly. We cannot go back in time to a single thought and think it again. Thoughts come and go at the speed of moments.
Knowing that singular focus of a thought is all we have, that this ability to hyper focus on one thing at a time, and even see clearly only a few degrees of sight, shows us that we humans must have used this as a great evolutionary advantage towards survival of some kind. If focus is a key to survival, and that one thought for one moment is all the energy we can muster for that moment, then knowing you have only that one moment of focus is a great revelation, in my opinion.
Taking the reigns of your thoughts will take great discipline, but to keep your series of thoughts focused on one problem or thought for as long as possible, will bring great clarity to you. We are designed in that way.