On 'truth" Buckle writes as follows: "A philosopher should aim soley at truth, and should refuse to estimate the practical tendency of his speculations. If they are true, let them stand; if they are false, let them fall. But, whether they are agreeable or disagreeable, whether they are consolatory or disheartening, whether they are safe or mischievous, is a question, not for philosophers, but for practical men. Every new truth which has ever been propounded, has, for a time, caused mischief; it has produced discomfort, and often unhappiness, sometimes by disturbing social or religious arrangements, and sometimes merely by the disruption of old and cherished associations of thought. It is only after a certain interval, and when the framework of affairs has adjusted itself to the new truth, that its good effects preponderate; and the preponderance continues to increase, until, at length, the truth causes nothing but good."
On the necessity of doubt Buckle writes "On this account it is, that although the acquisition of fresh knowledge is the necessary precursor of every step in social process, such acquisition must itself be preceded by a love of inquiry, and therefore by a spirit of doubt; because without doubt there will be no inquiry, and without inquiry there will be no knowledge? For knowledge is not an inert and passive principle, which comes to us whether we will or no; but it must be sought before it can be won; it is the product of great labour and therefore of great sacrifice.”
Because of "learned ignorance" Buckle argues that progress in Europe during the Dark Ages would have been faster if they had lost all knowedge of the alphabet."
Pages Vol. 1, xlii + 505 + 32 page catalog, Vol. 2, xii + 597, Vol.3, xvi + 548.