If the twentieth century is to be better than the nineteenth, it will be because there are among us men who walk in Priestley's footsteps....To all eternity, the sum of truth and right will have been increased by their means; to all eternity, falsehoods and injustice will be the weaker because they have lived.

Science is organized common sense where many a beautiful theory was killed by an ugly fact.

Perhaps no order of mammals presents us with so extraordinary a series of gradations as this [step by step, from humans to apes to monkeys to lemurs] - leading us insensibly from the crown and summit of the animal creation down to creatures, from which there is but a step, as it seems, to the lowest, smallest, and least intelligent of the placental Mammalia. It is as if nature herself had forseen the arrogance of man, and with Roman severity had provided that his intellect, by its very triumphs, should call into prominence the slaves, admonishing the conqueror that he is but dust.

Friendship involves many things but, above all the power of going outside oneself and appreciating what is noble and loving in another.

The quarrels of theologians and philosophers have not been about religion, but about philosophy; and philosophers not unfrequently seem to entertain the same feeling toward theologians that sportsmen cherish toward poachers.

Next to being right in this world, the best of all things is to be clearly and definitely wrong, because you will come out somewhere. If you go buzzing about between right and wrong, vibrating and fluctuating, you come out nowhere; but if you are absolutely and thoroughly and persistently wrong, you must, some of these days, have the extreme good fortune of knocking your head against a fact, and that sets you all straight again.

If individuality has no play, society does not advance; if individuality breaks out of all bounds, society perishes.