The decade of seniority Ludwig Feuerbach held over the scientific materialists is significant. His published works were already known to literary circles in the 1830's, to be sure as ardently Hegelian pieces, but even his philosophy of sensualism was in the hands of the public by 1845. Further, the ten years separating Feuerbach's university days from those of Karl Vogt correspond to noteworthy changes in German academe, changes symbolized by the death of Hegel in 1831. Feuerbach's university career began in 1823 and ended the year Hegel died, while Vogt did not begin his studies at Giessen until 1833. In order to become a proponent of materialism, Feuerbach had to undergo a conversion that was unnecessary for Vogt or Moleschott. Unlike Feuerbach, they never experienced the intellectual commitment to the idealistic, speculative philosophy of the 1820's.