It depends on what part of history we’re talking about but cats were considered both lucky and unlucky. Ancient Egyptians hailed cats as gods and cats have never forgotten this. In ancient Egypt it was a capital offence to hurt, harm or kill a cat and people who did this would be punished severely. Ancient Egyptians praised cats for controlling vermin and their ability to kill venomous snakes such as cobras, and the cat quickly became a symbol of poise and grace.
In Norse mythology, Freya was the goddess of marriage. She rode in a carriage that was pulled by two cats and the goddess is represented by a grey cat. Christians decided that Freya was a witch and a Pagan and her cats were seen as agents of Satan. Obviously the Christians saw the cats as unlucky and evil.
When soldiers came back from the Crusades, they brought black rats with them, (that caused the Great Plague and killed millions) and suddenly cats were needed again. This improved their image greatly.
Throughout the ages, people have always thought that cats possessed psychic abilities. Cat charms such as on a pendant have been thought to bring good luck and to help the wearer develop their own psychic potential.
There are many more stories and beliefs about cats being good luck and I tend to agree…afterall, a certain black cat crosses my path everyday.