How do we come to know what we know?
There is a physiological basis for our knowledge because what we know is based upon taking in sensory information that is then assimilated and accumulated in the neural networks in our brains. This might sound rather uninteresting, but it is a remarkable and fascinating process that results in a unique configuration of knowledge for each of us.
Even before we are born, our neural networks, which are a collection of neurons that connect and communicate with one another, are developing through sensory input. The sensory input, from the nerve endings throughout our bodies, is processed and stored in the brain. This is likely why the very youngest infant responds immediately to its mother, because her voice, for example, is already sensory input that has been stored.
Once one is born, the sensory input increases dramatically; new sights, sounds, smells, tastes, and tactile sensations are flooding the brain. The brain creates pathways amongst the neurons that allow storage and then retrieval of this "knowledge" when called upon.
Picture your brain as a series of files on your desktop. You create a new document and you put it in a file. Now imagine that you might put that new document in a few different files. If the document is in a few different files, it will be easier for you to find it later, having a few different paths to pursue to get it. The same thing is happening in your brain. You meet a new person. This person has dark hair, is female, is from New York City, and has an Asian name. Your brain files all of this information in different categories that reflect these attributes, and when you see this person again, you could be drawing on any of these "files" to remember her. The more different files you put knowledge in, the more neural connections you have to draw upon to retrieve this knowledge.
While your brain is doing this on its own, you can use your understanding of how it works to consciously strengthen the associations and connections that your brain makes. At the most primitive level, for example, we write the multiplication tables and recite them, over and over again. Writing them and reciting them makes two forms of sensory input in our brains, which means more connections for us to draw upon later on. Another example is learning about history. If we can make connections between historical events or connections of those events with our own lives, we are much more likely to retain that knowledge. I always connect the Civil Rights Movement with the Vietnam War, for example.
The strongest form of storage occurs when there is some heightened emotion surrounding the sensory input, for example, love or hate. When there is a heightened emotion, the brain's chemical response is more complex, and different parts of the brain are engaged, creating stronger knowledge and memory. This is likely to be the basis of post-traumatic stress disorder, which makes us keep memories we would rather not have.
A good teacher will help you acquire your knowledge by trying to understand what "files" there already are in your brain, to help you store new information in those existing files. And you can help yourself by doing the same!