Book 1, Sutra 6: Patanjali’s Yoga Sutra
“THE FIVE TYPES OF FLUCTUATING THOUGHTS ARE PRAMANA, VIPARYAYA, VIKALPA, NIDRA AND SMRTI.”
Patanjali will dedicate the next series of sutras defining each of these terms so I won’t make the attempt here. For now it is enough to know that each of these types of thoughts involve some type of knowledge or in other words, awareness of characteristics of the world, that fluctuate and can cause either pain or pleasure. These are the very things (VRTTIS, in Sanskrt) that Patanjali said in the earlier sutras that must subside if we are to disconnect from them and get re-established in our true natural unlimited state.