Complicated and controversial, cannabis is revealed by recent science to have a dual personality, with a dark side and a more positive one. Key to understanding this strange plant are two of the ingredients that make it up, known by their initials as THC and CBD. The THC makes you stoned, but it can also make you anxious. It can also make you feel a bit psychotic, and it will seriously impair your memory. The other side of the yin/yang is CBD, which has almost the opposite effects. CBD calms you down, it has anti-psychotic properties and it also offsets the effects on memory, so that on CBD-containing cannabis you're less likely to forget what's going on.