A bridge does not equal a tollbooth. Or does it? At what point does a toll booth become a bridge and vice versa. The only difference between them is in a tollbooth they steal your money. An easy pass makes a toll booth even closer to a bridge. What is a bridge anyway? Something one goes under? A large animal known to its ferocity? One sure can pass under one of those. Something used to cross over something? That would make my legs a bridge. And any airplane for that matter. 

Why do we define things by what they do rather than what they are? Because everything does something, not everything really exists.

Existence is deciphered through experience. Do things exist without us perceiving them? We don’t know, we can only speculate. A tree makes no noise if it falls in the forest, given I am not standing there experiencing the sound. Also making everything outside of my room invisible right now. I am deaf to 99.99% of the noises on earth right now. So exactly how far do our senses take us? Do we have only 5 senses? Or an extra that we can not perceive? It’s all speculation, thats all that life is, speculation with an expiration date.