In sanity

I finally finished reading and taking notes on Kierkegaard's Fear & Trembling (hopefully more to come later), and found this passage tucked away toward the end.

'nullum unquam exstitit magnum ingenium sine aliqua dementia' ['there was never great genius without some madness']. For the dementia here is the genius's suffering in life, is the expression, if I may say so, of divine jealousy, while genius itself is the mark of divine favour. Thus the genius is disorientated from the start in relation to the universal and put into relation to the paradox, whether, in despair over his own limitation, which in his own eyes turns his omnipotence into impotence, he seeks a demonic reassurance and therefore will not admit the limitation to either God or man, or he reassures himself religiously in love for the divine. There are psychological topics here to which it seems to me one could happily devote a lifetime, and yet we so rarely hear a word about them. How is madness related to genius? Can the one be constructed out of the other? In what sense and to what extent is the genius master of his own madness?