Here's a different thought. What is the limit of our species intelligence? Just like a beaver doesn't have the capability of pondering the meaning of its life, or invent a smartphone. What can we never do? what are we unable to think about? It must be something obvious and second nature to an alien species of higher intelligence. To them, we're ants in an ant hill, blissfully unaware of our true surroundings. And of course, I'm not talking about stuff like being unable to invent time travel, or discovering different dimensions. Those fantastical concepts are things we can imagine. We're capable of their basic understanding. But, you could argue, there is possibly an intellectual threshold that we have passed. All beings who pass this are capable of understanding and thinking about everything with enough time, and technological advancement. Because I thought of this to begin with, does that mean we have passed that threshold. Well, I believe that's an incredibly arrogant way of thinking. We're top dog on our mud ball, so we've gotten conceited. There's no space federation. No visiting aliens coming here, and saying hi. What would you do if you saw an ant hill? Would you think about talking to them and forming a human-ant alliance? No! You'd walk past, and possibly step on some of them. There must be creatures so intelligent, that we're not even like amoebas to them. Or maybe high intelligence isn't even a fraction of what's needed. What if we're missing something entirely different. Then, we wouldn't even amoebas to them. We'd be nothing but blades of grass.