Secret, Hidden, Obscured, or Perhaps in Some Cases, Even Purposely Disguised

Some of these teachers we know and in a sense are not secret at all. Yet in many cases what they have to teach remains so. Some are not so well known, indeed, are hardly known at all. One can be a secret teacher in the sense of being unknown, but one can also be a secret teacher in the sense that what you teach is secret, hidden, obscured, or perhaps in some cases, even purposely disguised.

Gary Lachman
The Secret Teachers of the Western World