The Hebrew Alphabet, as previously explained, has a numerical basis, so that, in truth, every Word as well as every Letter is really expressive of a number. Again, any two Words having a similar Numerical Value may be said to have a natural affinity through their vibration. This is the basic idea of what is called GEMATRIA and upon it a system of interesting Correspondences has been built up, especially in regard to the Hebrew Scriptures and other Qabalistic writings, wherein a Word or even a Sentence may be made to disclose some hidden meaning (often concealed in that way by the writer) by finding the numerical correspondence between it and other words or sentences of like value.  […]

Source:  Cabala and Gematria