Natural science will in time incorporate into itself the science of man, just as the science of man will incorporate into itself natural science: there will be one science.

• The ruling ideas of each age have ever been the ideas of its ruling class.
• Art is always and everywhere the secret confession, and at the same time the immortal movement of its time.
• It is absolutely impossible to transcend the laws of nature. What can change in historically different circumstances is only the form in which these laws expose themselves.
• Experience praises the most happy the one who made the most people happy.
• Necessity is blind until it becomes conscious. Freedom is the consciousness of necessity.
• The country that is more developed industrially only shows, to the less developed, the image of its own future.
• Greek philosophy seems to have met with something with which a good tragedy is not supposed to meet, namely, a dull ending.
• Anyone who knows anything of history knows that great social changes are impossible without feminine upheaval. Social progress can be measured exactly by the social position of the fair sex, the ugly ones included.
• On a level plain, simple mounds look like hills and the insipid flatness of our present bourgeoisie is to be measured by the altitude of its great intellects.
• The first requisite for the happiness of the people is the abolition of religion.