Neither the Church nor modern public opinion condemns petting, provided it stops short at a certain point.

The scientific attitude of mind involves a sweeping away of all other desires in the interest of the desire to know.

To modern educated people, it seems obvious that matters of fact are to be ascertained by observation, not by consulting ancient authorities. But this is an entirely modern conception, which hardly existed before the seventeenth century.

So far I have been speaking of theoretical science, which is an attempt to understand the world. Practical science, which is an attempt to change the world, has been important from the first, and has continually increased in importance, until it has almost ousted theoretical science from men's thoughts.

Men fear thought as they fear nothing else on earth - more than ruin, more even than death.

Do not fear to be eccentric in opinion, for every opinion now accepted was once eccentric.

Thought is merciless to privilege, established institutions, and comfortable habit.