Cats are creatures of the night, often sleeping and dreaming in the daytime while going out at night to hunt. Because of this association with the night they are often represented as mysterious and magical. Cats are often depicted with witches and this is often related to shape shifting - i.e. a witch taking the form of a cat when they wish to. Cats are often in fairy stories as wise or cunning creatures. In many traditions, such as in Egypt (see Bast), the cat was worshipped or held in very high esteem.
To wear or have near you the symbol of cat is to state your intention to commune more with your deeper magical self and to connect more with your dreams. The energy of cat is mainly about intuition and accessing our subconscious.