D-block (for diffuse) elements consist of the transition metals (group 3-12 on the periodic table) in which the outermost electron shell is the D orbital. D-block elements form at least one stable ion with an incompletely filled electron subshell.
... which deals with his life up to the time of his settlement at Königsberg.
See Quabicker, Karl Rosenkranz (1899), and J Hutchison Stirling, The Secret of Hegel, part ...