Why is Tantra A Secret?

Two weeks ago we gave the talk called "how to perform the best Tantrik ritual & overcome superstitions in Tantra" where we referenced Swami Vivekananda saying in the Introductory Chapter of Raja Yoga that mystery-mongering and superstition weakens the mind: everything that is could she be taught openly, and preached in the street in the broad daylight of reason. In that lecture, I argued that in some case the secrecy of Tantra was the attempt of an unscrupulous few "to keep the power all ...