We have sight, hear, feel, and taste. These are the senses we have and we use this everyday. We use sight to see, taste to eat, feel to touch and hear to listen. We have to use these senses definitely to study, for knowledge.
First we have to have sight to learn. Sight is everything. We look at the board to see what the teacher wrote and look at books to see the problems. If we did not have sight, our possibilities for knowledge would be limited into few things. We would not know what the world is like. We would not know anything.
Secondly hearing is very important too. We have to listen to know. If we did not have hearing, we would not know how people talk and how animals cry. We would not know how buildings collapse, balls hit etc. We would not know what the teacher is saying and we would not know about accents.
We would never be able to speak. If we did not have the sense of hearing our world would be a small thing.
The next is feeling. We would not know what hot and cold would be like if we didn't have the sense of feeling. What would be rough and what would be soft? We would not be able to learn science, which we touch a lot of things for experiments. Nothing would hurt but that is very dangerous. Our skin hurts when you cut yourself or touch something hot. That is because it is telling you it is dangerous. If we didn't feel anything we would die easily by burns etc. and our world would be cold.
The last is taste. This is very important too. Some people say we would become healthy if we didn't taste anything because we would be able to eat vegetables which most people don't like, but that is not true. We would be able to eat anything which is a very dangerous thing. Our tongue senses edible stuff and non edible stuff which helps you to live. For example we can not think about eating rocks. This is because your tongue senses this and it tells your mind that you can't eat it. We would not be able to do experiments too, because we taste a lot in science experiments. We would die easily just like feelings if we didn't have this. Our entertainment eating would disappear too.
We have to have all 4 senses for knowledge. These 4 are essential and nothing could be missed. If something is missing, our knowledge would be limited. Which gives you a hard time. But the most important thing you need is the brain which controls every sense.