Sentence:  It would in time, it is to be hoped, effect a quiet <WSD>euthanasia</WSD> of the heresies of bigotry and fanaticism which have so long triumphed over human reason, and so generally and deeply afflicted mankind; but this work is to be begun by winnowing the grain from the chaff of the historians of his life. 
Meaning of the word marked with <WSD> tags:  An easy death, or the means to bring about such a death.