After shedding his individuality, the Yogī moves further up towards final liberation and begin to feel that he is Śiva.
Vitarka ātmajñānam वितर्क आत्मज्ञानम् (sūtra I.17)
Vitarka – firm consciousness (vitarka literally means reasoning, deliberation, etc); ātmajñānam – knowledge about the Self (Ātma).
“I am Śiva” is the knowledge that is spoken of here. The Yogī, without any obturation to his consciousness firmly affirms that he is Śiva. When the mind is afflicted with other thought processes, this kind of affirmation is not possible. As the Yogī has already fixed his perpetual consciousness on Paramaśiva as discussed in the previous aphorism, he is able to affirm that “I am Śiva”.
Spanda-Kārikā (II.7) says that this is the initiation of the process of liberation, leading to the merger with Śiva, where non-dualism is completely vanquished. This is known as nirvāṇa.
Vijñānabhairava (109) also says, “The Highest Lord (Prameśavara) is omniscient (sarvajñaḥ), omnipotent (sarvakartā) and omnipresent (sarvavyāpakaḥ). Since I (the Yogī) have the attributes of Śiva, I am the same as the Highest Lord. With this strong belief, one becomes Śiva.”
When the Yogī consciously affirms that He is Śiva, all the dualities in his mind are dissolved, as a result of which Śiva alone prevails. As a result of this mental state, i.e, dissolution of all the dualities in the mind of the Yogī, the subject also becomes Śiva for him. This is possible only by conviction rather than reasoning. Reasoning does not arise in him because, he sees only Śiva everywhere, as both subject and object is Śiva for him.