Om Namasivaya nama:
Title : Thamo Guna Nature and Effects (Lethargic stage)
The Veiling power (Avruthi or Avarana) is the greatest string of Thamo Guna, which is nothing but make things appear to be other than what it actually are; a kind of illusionary projection in one's own mind. It creates repeated transmigration and initiate the action of the projecting power known as Vikshepa sakthi. Rajas will grow and take the position Thamas in other words Rajas will create agitation in mind and Thamas will veil the reality these are the two important plays of Maya (Rajas-Vikshepa/Projecting and Thamas-Avarana/Veil). Therefore the student of Vedantha must understand the power of these Gunas and apply discrimination accordingly to over come Gunas (Qualities).
Please down load full discourse from the below link.