The Silver Cord is a legendary concept that states two people who are soulmates are bound by a silver cord that only they can see and experience.
The Silver Cord is present in the novels, between Cassie Blake and Adam Conant. It is apparent that the two have a deep connection, as noted by the silver cord between them, which Cassie notices when she first meets Adam in The Initiation. The significance of the silver cord is, however, only revealed in The Power by Melanie and Diana, who explain to Cassie and Adam that they are soulmates and destined together.
The concept of the silver cord does not appear to exist within the TV series, however, it has been stated several times that the Blakes and Conants are fated to be together - a concept very similar to the Silver Cord.
- The Soulmate Principle is not unique to The Secret Circle, as it appears in other works of L. J. Smith such as The Vampire Diaries and Night World.
- Night World in particular centers around the Soulmate Principle and its significance to the destined soulmates.
- At the end of The Power, Cassie sees what she believes is a silver cord connecting the Circle, implying that they all are soulmates. While it is not the same as Cassie and Adam's, this kind of soulmate relationship is more of a karmic one; soulmates that are not necessarily romantic but provide each other healing and understanding as well as being spiritually connected to each other's lives.