The emerald tablet spells out "That which is below is like that which is above and that which is above is like that which is below to do the miracle of one only thing." The common phrase derived from this is "As above, so below". The meaning I find in this phrase is that we live within the inner world of our mind, and only through that world can be glimpse the outer world of physicality. It's also said that we are a microcosm, and the rest of the world is the macrocosm, and between these two there are clear links. Everything that we experience in the external world around us is represented in the mind. In many cases, it is this inner mental world that shapes our understanding of and ability to interact with the external world.
Let's have a story to illustrate this concept. Albert was a small child when he was bitten by a dog. There was no warning, and the dog had previously wagged its tail and licked his face. Burned into Albert's mind is the image of the dog baring its fangs a split-second before it bit him. Albert can reason that dogs are generally safe animals, but can't shrug off the gut feeling he gets when he sees dogs. He can't help but notice the strong jaws and sharp fangs they have at their disposal. Betty, however, grew up in a household of seven large dogs who were all wagging tails, drool, and puppy dog kisses. Albert and Betty were each made an offer they couldn't refuse: a million dollars to babysit twenty large dogs at a farmhouse. Betty spends this time enjoying taking care of what she sees as big puppies. For Albert, however, this is Hell. He is entering the proverbial den of lions, and has to wonder if any sum of money is really worth risking his life. Sure, dogs are safe, but this many? Surely, one of them will go rogue. Surely, this is the perfect storm to be bitten by a dog.
One more story. Charles finds himself a prisoner in a dark, dank cell at the bottom of a castle. Thick iron bars form the walls of his cell, and he has tried every trick in the book to bend, file, or even rust them. Nothing has worked, and a year has passed. Every morning, the guards bring a tray of food and slide it in through a gap in the heavy iron door. The other prisoners will pound on the bars of their own cells, and some even smuggle in lock picks and attempt to pick the locks on their doors, but they don't make any more progress than Charles. One day, the guards come and drop off a woman into Charles's cell. She introduces herself as Denise and asks whether Charles has considered escape. Charles explains how the bars are too sturdy to break, and even his neighbors with lockpicks couldn't get their doors open. Denise thinks about this for a time, then walks up to the door. and turns the knob. It opens. "It looks like ours wasn't actually locked." There is no wall, no lock, no prison more effective than the ones we construct in our minds.
Edward was too young to remember his life before he was raised by wolves in the wild. What he did know is the stringy taste of raw meat, of eating wild berries, and of occasionally finding roots. One day, hunters found Edward in the wild and took him back to the nearest city. The hunters were shocked to find that Edward still remembered bits and pieces of English despite his upbringing. He even knew his name. "Hungry" Edward said, so the hunters brought him to a small convenience store on the edge of town. The hunters instructed Edward to pick out whatever food he wanted, and they sent him into the store. He found no fresh meat, no berries, and no roots. There were only plastic bags and cardboard boxes containing a variety of strange objects that Edward frankly could not remember ever encountering in his life. Dispairing, Edward returned to the hunters to inform them "No food". One of the hunters laughed, opened a sleeve of crackers, and handed it to Edward. "Food."