Thinking (in the sense that we are here talking about it) means three things, 1. having (having experienced, having been reached and claimed by) a thought; 2. absolute obligation to and constraint by this one thought, no freedom, necessity; 3. potential openness to any and all phenomena of life in the light of one’s single thought.
Giegerich defines thinking not as a cognitive function but as an existential and logical event of being seized by, and wholly committed to, a single commanding thought.
, The Soul’s Logical Life Towards a Rigorous Notion of, 2020thesis