What's one thing that without it people wouldn't be able to interact with their environment?

Actually it is not one, it's five: the senses.

I was walking yesterday trying to figure where an annoying sound was coming from. I first thought it was coming from one direction, but further tuning in showed the origin of that sound. My mind almost instantly imagined the device that could cause such an itchy noise.

This lead to another insight. Somehow I realized that because of the walls surrounding the place I was in, I could not see where the sound was coming from... of course I could not taste, smell nor touch it, either, which couldn't give me any more information on the source. Further into philosophizing about the topic I realized that of all senses hearing and the sense of smell are the ones that can locate things coming from further away. On the other hand touch and taste the ones that are more short range.

Photo from Wikimedia

Amazing what little attention does to our interactions with the world. How many people are actually aware, consciously aware of all the stimuli that the world is offering ALL the time. Maybe this point is the reason why so many aren't (aware). There is soooo much of it: sounds, smells, tastes, sensations, and unless you can't use your eyes, visuals. It's like a little machine working all the time (perhaps except while asleep), feeling, feeling, feeling. No wonder why some people are unable to feel... could it be too much?

I mean, some people just switch off and live automatically. Their minds are overly active, disconnecting the feeling. It's as if there was a little command that said... too much information, just grab what it is important and let go of the rest. But, what is important?

Have you seen people on rush hour... they barely look alive, you can feel their minds (ok, I've been there too) moving at the speed of light... blahblahblah... There's a world out there and most people barely notice... it's all in their heads!