Perception is the brain’s way of organising information and putting it into context, creating meaning out of our senses. Without our brains to process signals, our senses would be useless.
The brain organises and translates the data our senses send in order to make meaningful perceptions and calculate an appropriate response. Take the eye for example — without the brain to process the upside-down pictures coming through, we would never understand what we were looking at.
Perceiving something is what happens after seeing something, and indeed it is not seeing, but perceiving that is believing.
From Crash Course: Psychology on YouTube presented by Hank Green