If it were not for collectors England would be full, so to speak, of rare birds...

If it were not for collectors England would be full, so to speak, of rare birds and wonderful butterflies, strange flowers and a thousand interesting things. But happily the collector prevents all that, either killing with his own hands or, by buying extravagantly, procuring people of the lower classes to kill such eccentricities as appear. ...
Eccentricity, in fact, is immorality--think over it again if you do not think so now--just as eccentricity in one's way of thinking is madness {I defy you to find another definition that will fit all the cases of either}; and if a species is rare it follows that it is not Fitted to Survive. The collector is after all merely like the foot soldier in the days of heavy armour-he leaves the combatants alone and cuts the throats of those who are overthrown. So one may go through England from end to end in the summer time and see only eight or ten commonplace wild flowers, and the commoner butterflies, and a dozen or so common birds, and never be offended by any breach of the monotony.