The more distinct of these intra-national groups may not only be very fully isolated from the common body, but may be the seat of an actual corporate hostility to it, or rather to the aggregated minor groups which have come officially to represent it. When war breaks upon a society thus constituted {216} the intense stimulation of herd instinct that results tends to break down the moral restrictions set up by segregation, to throw back the individual citizen on to the nation at large for the satisfaction of his moral needs, and to replace class feeling by national feeling. The apprehended danger of the given war is the measure of the completeness with which occurs such a solution of minor groups into the national body. The extent of such solution and the consequently increased homogeneity it effects in the nation will determine the extent to which national feeling develops, the degree to which it approaches unanimity, and consequently the vigour with which the war is defended and conducted. If a minor group has already developed a certain hostility to the common body and resists the solvent effect of the outbreak of war, it becomes a potential source of anti-national feeling and of opposition to the national policy. Surrounded as it necessarily will be by an atmosphere of hostility, its character as a herd becomes hardened and invigorated, and it can endow its members with all the gifts of moral vigour and resistiveness a herd can give. Thus we may say, that in a country at war _every_ citizen is exposed to the extremely powerful stimulation of herd instinct characteristic of that state. In the individual who follows in feeling the general body of his fellows, and in him who belongs to a dissentient minority, the reactions peculiar to the gregarious animal will be energetically manifested. Of such reactions, that which interests us particularly at the moment is the moulding of opinion in accordance with instinctive pressure, and we arrive at the conclusion that our citizen of the majority is no more—if no less—liable to the distortion of opinion than our citizen of the minority. Whence we conclude that in a country at war _all_ opinion is necessarily more or less subject to prejudice, and that this liability to {217} bias is a herd mechanism, and owes its vigour to that potent instinct.