We all start our life with a misunderstanding about the fact of our existence and that of the universe.
We can see when we are born and are completely unable to think and develop an understanding. The part of our brains with the function of thinking takes time to develop and it is thinking that leads to understanding while sense perception only feeds us individual and disjointed bits of information about the external universe.
The nature of sight is that it sees individual forms. Indeed that is the nature of all the senses of perception; they can only perceive small parts of the whole. When we begin our lives, we do have the ability to see beyond what the senses present to us. Thus, we grow up thinking that we are our body, separate from that of the others
My body is me and your body is you. There is nothing connecting us with each other. When we are able to perceive our mind, we understand the same of it. We all thus grow up thinking of ourselves as finite body-mind individuals disconnected from the others in our environment. There is no exception to it.
What then is the truth? We all and this entire universe is from an invisible and subtle reality which causes us to exist and having done so inhabits every minutest part of our being just like energy pervades every atom without which there can be no atomic integrity. That unseen cause permeates and connects us with all existence comprising of the sentient and insentient beings. No sentient being thus is immune to our existential misunderstanding.
Essentially this misunderstanding leads to an identification of our existence merely to that of the physical body. Body is finite and identifying with the body alone, we feel small and helpless. While being much more than the body, we think we are body alone. Body is weak and subject to pain, it falls sick, it decays and it dies. With our identification with the body-mind complex alone, focus of life remains limited to day to day survival issues addressed reactively without examination of our behaviour and consideration of what is good at an ongoing basis.