Secondly, we have the bias of nation, rank, party, sect. Here the mental disturbances are too numerous to permit and too obvious to require special exemplification. Intellectual provincialism of any kind is fatal to large and fertile thought, alike by limiting the range of our knowledge and sympathies and by inducing mental habits and implanting prejudices which prevent us from seeing things in wide relations and under a clear light. So long as our point of view is simply that of our country, our class, our party, or our church, so long, it is evident, our minds will lack the breadth and flexibility necessary for free inquiry, fruitful comparisons, sane and balanced judgments.[24] [Footnote 24: _Cf._ Spencer's Introduction to the Study of Sociology, chapters viii-xii.] Finally, among the Idols of the Cave "which have most effect in disturbing the clearness of the understanding," mention must be made of the temperamental bias. Every man, it has been said, is born Platonist or Aristotelian; it is certain that the great divisions in thought--religious, philosophical, political--answer roughly to fundamental differences in human nature, and that every one not checked or turned aside by extraneous influences will spontaneously gravitate in one or another direction. Bacon is only recording a fact of the commonest experience when he says that "there are found some minds given to an extreme admiration of antiquity, others to an extreme love and appetite for novelty, but few so duly tempered that they can hold the mean, neither carping at what has been well laid down by the ancients nor despising what is well introduced by the moderns." Many instinctively brace themselves against authority and tradition; by others again, whatever is handed down to us by authority and tradition is for this reason alone treated with contempt. That the crowd believes a thing is enough to convince this man of its truth, and that of its falsehood. "The vulgar thus through imitation err; As oft the learned by being singular."