A recent biography of Leavis by Ian MacKillop explains that, after he had delivered his insulting lecture, calling Snow as intellectually undistinguished as it is possible to be, the Spectator wanted to publish it. Lawyers warned that it was libellous, so Sir Peter Medawar - a friend of Snow’s - was sent as an intermediary, to obtain permission. As Snow was suffering from a detached retina he could not read it himself, but his wife read it to him and, although evidently hurt, he immediately said it should be printed in full, displaying admirable magnaminity, a virtue completely alien to Leavis.
It was generally agreed that literary critic F.R. Leavis went a little bit over the top in his 1962 response to C.P. Snow's 1959 Rede lecture on the "two cultures". In his identification of the widening gulf between the cultures of science and the humanities, Snow, despite his credentials as a novelist, had let his pro-science bias shine through in a way that obviously got Professor Leavis's goat. F.R. Leavis's reply was memorable, though possibly more for the sheer vituperation of his attack than for the quality of his arguments. According to Leavis, Snow
doesn’t know what he means, and doesn’t know he doesn’t know. The intellectual nullity, is what constitutes any difficulty there may be in dealing with Snow’s panoptic pseudo-cogencies, his parade of a thesis: a mind to be argued with that is not there; what we have is something other. ... As a novelist, he doesn’t exist; he doesn’t begin to exist. He can’t be said to know what a novel is.