Which preposition to use with disproof

of Occurrences 12%

He held that the idealized marriage relationship was not merely the symbol, but the most effectual sacrament and instrument of that love; "yet the world," he complains, "goes on talking, writing, and preaching as if there were some essential contrariety between the two," the disproof of which "was the inspiring idea at the heart of my long poem (the 'Angel')."

Which preposition to use with  disproof