The more one thinks, the more one feels the hopeless immensity of man's ignorance.

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 no valid objection that science as yet throws no light on the far higher problem of the essence or origin of life. Who can explain gravity? No one now objects to following out the results consequent on this unknown element of attraction.

In the struggle for survival, the fittest win out at the expense of their rivals because they succeed in adapting themselves best to their environment.

The plow is one of the most ancient and most valuable of man's inventions; but long before he existed the land was in fact regularly plowed, and still continues to be thus plowed by earthworms. It may be doubted whether there are many other animals which have played so important a part in the history of the world, as have these lowly organized creatures.

From my early youth I have had the strongest desire to understand or explain whatever I observed. ... To group all facts under some general laws.

So in regard to mental qualities, their transmission is manifest in our dogs, horses and other domestic animals. Besides special tastes and habits, general intelligence, courage, bad and good tempers. etc., are certainly transmitted.