Cannabis induces your brain's frequncies to the alpha state. This is perfect for creativity.

alpha 8-12 Hertz Relaxed: The most widely known and publicized is the Alpha wave. Most people equate this wave with ESP, meditation, and all sorts of strange ideas. The truth is the alpha waves account for only half the story. Alpha ranges between 7-12 hertz and is prominent during relaxation mostly with eyes closed, day dreaming, and upon deep self-introspection. The 1960's made this activity famous when it was found out that cannabis or marijuana, which grew naturally, induced this state in people. Scientist have found out that it was the chemical THC that caused this euphoric feeling by being a substitute for the brain's natural pleasure chemicals which are called endorphins.

Out of all the different types of brain waves there is a very interesting range called the Alpha-Theta border. I've already mentioned that the Alpha was half the story, well the Theta wave is the other half of a state of mind that brings about creativity, intelligence, and a host of other abilities the brain is capable of doing when properly stimulated.

Many cultures discovered this and the methods to achieve this state naturally and artificially. Many of the worlds religions were founded on reaching this state and devised strict disciplines to do so. The Alpha-Theta range occurs during reverie, hypnogogic imagery, meditation, and by self-hypnosis. The drugs that achieve this state are controlled use of cannabis and hallucinogens.