If philosophy is practice, a demand to know the manner in which its history is to be studied is entailed: a theoretical attitude toward it becomes real only in the living appropriation of its contents from the texts.

Jaspers links philosophy to lived activity rather than mere doctrine. If philosophizing is a “practice,” then studying philosophy’s history cannot be a neutral catalog of positions; it must ask how one is to read and learn from past thinkers. For Jaspers, a purely “theoretical attitude” toward philosophical history remains abstract unless the reader actively appropriates what the texts contain—making their questions and insights one’s own in the present. The quote thus argues for a hermeneutic, existential engagement with philosophical classics: understanding is not complete until it becomes a mode of thinking and living, not just information about what others once thought.