What event is SJ Gould describing in this paragraph? “Thus d…

What event is SJ Gould describing in this paragraph? “Thus did the second unmasking begin in the transposed home and living presence of the first – and the ghost of Linnaeus smiled (being more generous and ecumenical than the great Swede in life) as Darwin’s words revealed a causal basis for the natural order that Linnaeus had codified. And the psalmist intoned his ancient song: “Behold, how good and how pleasant it is for brethren to dwell together in unity!”