Stefan Lang recently published a valuable contribution in the Deutsche Zeitschrift für Philosophie on the discussion between Mendelssohn and Kant on the validity of the ontological proof for the existence of God. The conclusion of his article contrasts with that defended by the author of these pages in an essay published in Kant-Studien a few years ago. Our discrepancy is based on two closely related key issues: firstly, on how to interpret Mendelssohn’s thesis that the absolutely necessary being is both (...) thought and thing; secondly, on the significance and scope to be attributed to Kant’s thesis of the impossibility of an ontological proof of God’s existence. (shrink)