 Two traditions can be traced in the wake of Descartes’s reflections. Beginning with the De solido intra solidum naturaliter contento dissertationis prodromus of 1669 by the Danish Cartesian Nicholas Steno (1638–86), efforts commenced to draw the historical origins of living beings into the Cartesian cosmology, in this case primarily by granting that fossils were the remains of once existing organisms on an earth that had formed historically. There was, however, no effort made to account for the origins of these beings on Cartesian principles (Rudwick 1972).