viparyayaḥ – erroneous understanding of what is, misconception; mithyā – false; jñānam – knowledge; atad – not that; rūpa – (true) form, essential nature; pratiṣṭham – based upon:
Incorrect knowledge formed about something, which is not based on its true nature, is called false understanding (misconception).
The incorrect knowledge or erroneous understanding spoken about here refers to the idea of mistaking something for something else. A common example used in the Vedas is that of a rope and a snake; that if one comes across a rope on the path home at night, and it is quite difficult to distinguish, I may imagine it to be a snake. What I’m doing is superimposing the form of a snake onto something that is not a snake, and even though a snake is a real thing and rope is also a real thing, the superimposition itself affects the mind causing a vrtti, and this vṛtti is an error. There are unlimited ways in which this vṛtti can be manifest or be experienced, as will become revealed on our journey through the sūtras. Vyāsa considers incorrect knowledge to be synonymous with the five kleśas as we will discover going forward.