First among such principles is the recognition of the fact that prejudice does not display itself as such to direct introspection. One who is being {221} influenced by prejudice will never be able to detect his biassed judgments by an apparent defect in their plausibility or by any characteristic logical weakness. Agreement or disagreement with common opinion will as such be no help, since prejudice infests minorities no less than majorities. To suppose that when one has admitted the liability to prejudice one can free oneself from it by a direct voluntary effort is a common belief and an entirely fallacious one. Such a task is far beyond the powers of the most fully instructed mind, and is not likely to be undertaken except by those who have least chance of success. Prejudice, in fact, is for the individual like the ether of the physicist, infinitely pervasive and potent, but insusceptible of direct detection; its presence is to be assumed as general, but it escapes before immediate search by introspection as the ether eludes the balance and the test-tube. Secondly, it is possible for the investigator, having admitted the existence of prejudice as a condition of thought, to recognize the general direction of its action in his own mind, to recognize, that is to say, whether the tone of it is pro-national or anti-national, and thus to obtain a certain orientation for his efforts to neutralize it. Having frankly recognized this general tendency in his thinking, he will be able to do something towards correcting it by making allowance for it in his conclusion as a whole. If his tendency of feeling is pro-national, he will say to himself of any judgment favourable to his country, “This is a conclusion likely to have been influenced by prejudice, therefore for all the precautions I may have taken in forming it, and whatever scientific care and caution I may have used, in spite even of its agreeable appearance of self-evident truth, I must regard its validity as subject to some subtraction before it {222} can safely be made the basis for further speculation.” If his tendency of feeling is anti-national, he will have a similar task of attenuation to carry out upon the conclusions unfavourable to his country that he may reach, and will be prudent to make very drastic deductions in view of the supposed immunity to prejudice with which minorities are rather apt to assume the absence of vulgar approval endows them.[U]