Good question about dreams. In my hypnotherapy classes we did a lot of work with interperting dreams. While I agree that in the past practitioners of magic were considered "wise people", I believe that thanks to the internet and the printing press, people are practicing without the benefits of learning wisdom.
So, let's look at dreams. Yes, dreams are symbolic. The subconscious mind communicates using symbols. Now, there are all kinds of books on interpertation of dream symbols. They are all worthless. Useless garbage. There are some things that have a universal meaning such as the Jungian archetypes, but that does not mean your mind has learned them correctly or rewritten their meaning in your subconscious. Symbols are dynamic, not static. The best way to figure out the symbolism is not what a symbol means to whoever wrote a book, but what it means to you.
Now, dreams. People typically go through three dream cycles a night. You will drift down into a deeper level and dream and then come back up to a lighter sleep state, and then repeat. These are your REM cycles, and typically last anywhere from 90 to 120 minutes in length. At each stage your mind is doing something different.
The first stage is called the "Wishful Thinking" stage. This is where your mind, which has been taking in information all day, sorts the information and seperates what is to be kept from what is not necessary. Everything you have seen, heard, felt, tasted and smelled is sorted through. This is the stage that has the least effect on us, and since it is the first REM phase of the night, it is typically not remembered.
The second stage is the "Precognitive" stage. The mind takes the bits of information to be kept, and places them in your world-view of accepted knowledge and reality that is stored in your mind. It is like putting a puzzle together. You place a piece here and a piece there. Sometimes you find a piece that needs to be moved. Sometimes a piece is not needed at all and is removed. At some point, when you get enough pieces together, you get an idea of what the completed picture will look like. Now, you don't have all the pieces yet, but you mind is able to infer what the rest of the picture is. It is not always correct, of course. This is the origin of precognitive dreams. Sometimes these are remembered, and sometimes they are not.
The third phase is called the "Venting" stage. This is where the mind gets rid of all the information it does not need. It does so the same way it got the information to start with. The information came in through the five senses, and it is vented out through them as well. You re-experience them. Now, most people will move very little and just have REM during this phase. Some people will move, react, sleep walk and the like. This is due to Tonic Motor Inhibition, which basically allows the body to experience something without moving. Someone with a high TMI will not move during this phase, and someone with a low TMI will toss, turn, talk and have other reactions. All of the information that the mind considers of no use is dumped. Unfortunately for us, this is the cycle that is closest to our waking point, so it is the most easily remembered.
I am not going to go into the entire process of interperting the meaning of dreams here because it would take a short book to explain everything. In a nutshell, the process is (1) determine what phase the dream was in; (2) examine everything and see is things actually exist, or if it is something that does not exist, i.e. a symbol; (3) analize how the symbol makes you feel and what it brings up within you; (4) what kind of things are you experiencing that relate to those feelings or meanings; and finally (5) figure out what triggered the dream. Even with this brief outline you can get an idea of the steps and start to look deeper into the meanings of your own dreams.