The Doctrine of Secrecy or Silence in spiritual mysticism is a rule that suggests that the spiritual master/leader keep his knowledge of the 'wayfaring path' confined strictly to either themselves, or select close-knit disciples who the Master has adjusted worthy as being capable of following the wayfaring path (i.e. they seek to become a spiritual master themselves).
This knowledge is kept hidden from the world and includes but is not limited to: The liturgies/chants/meditations a Master prescribes for recitation, Divine Visions of Holy Personalities, Knowledge received through Inspirations, Unveiling of hidden truths , Mental, physical and spiritual abilities, Universality and Singularity of God etc.