I have never been able to understand why pigeon-shooting at Hurlingham should be refined and polite, while a rat-killing match in Whitechapel is low.

All knowledge is good. It is impossible to say any fragment of knowledge, however insignificant or remote from one's ordinary pursuits, may not some day be turned to account.

Every philosophical thinker hails it [The Origin of Species] as a veritable Whitworth gun in the armoury of liberalism.

Science is nothing but trained and organized common sense differing from the latter only as a veteran may differ from a raw recruit: and its methods differ from those of common sense only as far as the guardsman's cut and thrust differ from the manner in which a savage wields his club.

As for your doctrines I am prepared to go to the Stake if requisite ... I trust you will not allow yourself to be in any way disgusted or annoyed by the considerable abuse & misrepresentation which unless I greatly mistake is in store for you... And as to the curs which will bark and yelp - you must recollect that some of your friends at any rate are endowed with an amount of combativeness which (though you have often & justly rebuked it) may stand you in good stead - I am sharpening up my claws and beak in readiness.

Agnosticism, in fact, is not a creed, but a method, the essence of which lies in the rigorous application of a single principle. ... Positively the principle may be expressed: In matters of the intellect, follow your reason as far as it will take you, without regard to any other consideration. And negatively: In matters of the intellect, do not pretend that conclusions are certain which are not demonstrated or demonstrable.

Genius as an explosive power beats gunpowder hollow; and if knowledge, which should give that power guidance, is wanting, the chances are not small that the rocket will simply run amuck among friends and foes.