The Law of Similarity is the first of two sublaws contained within the Law of Association, the second is the Law of Contact or Contagion. The Law of Similarity states that like things produce like things, or that an effect resembles its cause.
Schematically this may be illustrated as such: thing “A” may produce something similar to itself called “C”; and, thing “B” may produce something similar to itself called “C”; and, this something called “C” may be shared by both “A” and “B”.
(See The Laws of Magic.) A.G.H.