Everything in nature is the result of fixed laws.

That there is much suffering in the world no one disputes. Which is more likely, that pain and evil are the result of an all-powerful and good God, or the product of uncaring natural forces? The presence of much suffering agrees well with the view that all organic beings have been developed through variation and natural selection.

Why, if species have descended from other species by insensibly fine gradations, do we not everywhere see innumerable transitional forms.

Although I am fully convinced of the truth of the views given in this volume under the form of an abstract, I by no means expect to convince experienced naturalists whose minds are stocked with a multitude of facts all viewed, during a long course of years, from a point of view directly opposite to mine... I look with confidence to the future, to young and rising naturalists, who will be able to view both sides of the question with impartiality.

It is interesting to contemplate an entangled bank clothed with many plants of many kinds with birds singing on the bushes, with various insects flitting about and with worms crawling through the damp earth and to reflect that these elaborately constructed forms so different from each other and dependent on each other and so complex a manner have all been produced by laws acting around us.

Building a better mousetrap merely results in smarter mice.

The main conclusion arrived at in this work, namely that man is descended from some lowly-organised form, will, I regret to think, be highly distasteful to many persons. But there can hardly be a doubt that we are descended from barbarians.