“The Kriya Yogi endeavors to constantly remain immersed in the holy sound Pranava, the Omkar; and the deeper the concentration attained in this effort the quicker is he able to get over the attributes of senses and ultimately above the veil of Maya, Delusion. The different higher Kriyas have been designed to gradually attain the highest stage in this respect. The different courses of Kriya techniques have been designed in such a manner that a Kriya Yogi proceeds towards perfection by passing through the stages of Dhyana (contemplation), Jnana (subtle experiences) Tyaga (renunciation) and Shanti (bliss)---- the four steps in the progress towards ultimate success.”
From "Kriya Yoga"