Only then, approaching my fortieth birthday, I made philosophy my life’s work.

Jaspers frames philosophy not as an early vocation but as a deliberate, mature commitment. The line suggests a turning point: only after years of other work and lived experience does he “make philosophy” his life’s work, implying that philosophical inquiry can be grounded in prior practical, scientific, or existential encounters rather than youthful abstraction. The mention of his fortieth birthday underscores the weight of time—philosophy here is a chosen orientation for the remainder of life, not merely an academic specialty. It also hints at Jaspers’s characteristic emphasis on existential “decisions” and boundary-situations: a life’s direction becomes clear through decisive self-appropriation rather than gradual drift.