Karl Barth wrote the following to his friend Eduard Thurneysen in 1922:
Calvin is a cataract, a primeval forest, a demonic power, something directly down from Himalaya, absolutely Chinese, strange, mythological; I lack completely the means, the suction cups, even to assimilate this phenomenon, not to speak of presenting it adequately.
What I receive is only a thin little stream and what I can then give out again is only a yet thinner extract of this little stream.
I could gladly and profitably set myself down and spend all the rest of my life just with Calvin.
-Karl Barth, Revolutionary Theology in the Making: Barth-Thurneysen Correspondence 1914-1925, trans. James D. Smart (Richmond: John Knox Press, 1964), 101.
Helpful perspective on the translation from the comments section below:
Markus Prieur: I am a native German speaker living in Ireland. In the original German quote (see below together with my alternative translation) “demonic” is a nominalized adjective in the neuter gender [which is probably the reason why "power" was added in the translated quote above]
“Calvin ist ein Wasserfall, ein Urwald, ein Dämonisches, irgendetwas direkt vom Himalaya herunter, absolut chinesisch, wunderbar mythologisch; es fehlen mir gänzlich die Organe, die Saugnäpfe, dieses Phänomen auch nur in mich aufzunehmen, geschweige denn richtig darzustellen.”
“Calvin is a waterfall, a jungle, a demonic, something directly down from Himalaya, absolutely Chinese, wonderfully mythological; I am lacking completely the organs, the suction cups to merely absorb this phenomenon, let alone to present it correctly.”
I don’t doubt that Barth meant ‘daemon’ (OED on the original Greek word: “a god, genius, tutelary spirit; a supernatural being of a nature intermediate to gods and men”). He is saying that Calvin seems to be a vast, uncanny force, beyond mere nature, a seeming demigod—not a ‘demon’ (in the sense of “an evil being”). He is admiring Calvin as inexplicably rich and large beyond our comprehension.