As humans, we have great abilities to perceive things (e.g., to see things happening far away, to hear sounds at a distance, etc.). However, we also have limitations. For example, eagles can see much, much better than humans. When we are presented with some information that is just below our conscious awareness but still reaches our brains, it is a subliminal message - meaning, the information is getting into our systems and to our brains without us truly being aware of it. You may be familiar with the idea of subliminal messages is advertising in which a message is flashed so quickly that we don't "think" we saw it (containing the message the advertiser wants us to get) but our brains actually processed it. The idea being that we will still respond to that message even though we didn't realize we saw it.