From Liberalism: In the Classical Tradition — surrounding passage

This, however, is a purely intellectual matter. It is a victory that can be won only with the weapons of the intellect, never by force. The suppression of all opposition by sheer violence is a most unsuitable way to win adherents to one’s cause. Resort to naked force—that is, without justification in terms of intellectual arguments accepted by public opinion—merely gains new friends for those whom one is thereby trying to combat.

“In a battle between force and an idea, the latter always prevails.”

Fascism can triumph today because universal indignation at the infamies committed by the socialists and communists has obtained for it the sympathies of wide circles. But when the fresh impression of the crimes of the Bolsheviks has paled, the socialist program will once again exercise its power of attraction on the masses. For Fascism does nothing to combat it except to suppress socialist ideas and to persecute the people who spread them.