Although the mind is one, it passes into many conditions or states, as it is made up of three qualities, Gunas, viz., Sattva, Rajas and Tamas. All these qualities enter into a variety of combinations. So, the modifications or Vrittis of the mind are also various. Peace of mind (Santa Vritti) is a Sattvic Vritti. Lust is a Rajasic Vritti. Laziness is a Tamasic Vritti. Anger is a Ghora Vritti.
Internal fight is ever going on between Gunas, Sattva, Rajas and Tamas; between good Vrittis and evil Vrittis. This is the internal warfare between Suras and Asuras.
When the lake is in a boisterous state on account of the turbulent waves, you can hardly see the bottom of the lake. When the waves subside, you can clearly see the bottom of the lake. Even so when the mind is in an agitated condition on account of various Vrittis, you can hardly rest in your own nature. You cannot see or realise your own Self. But when the Vrittis subside, you can rest in your own state. You do not identify yourself with the Vrittis now. Then means when all the Vrittis subside or done through Chitta Vritti Nirodha.
By suppressing the transformations of the mind, the Sadhaka acquires great Siddhis. He becomes an adept or a great Siddha. Yoga is a complete suppression of the tendency of the mind to transform itself into objects, thoughts, etc. It demands continuous and steady practice. Then comes unlimited strength, peace, bliss and knowledge. This leads to Asamprajnata Samadhi and Kaivalya, the highest stage of Raja Yoga.
by Swami Sivananda