Small, deliberate actions practiced consistently can lead to big changes in happiness levels.

States are rational actors that seek to maximize their power and security in an anarchic international system.

I am convinced that the substitution of a simple tax on the rent of land for the complicated taxes which at present oppress industry would be advantageous to all classes.

The only way to learn mathematics is to do mathematics.

The body is not a thing, it is a situation: it is our grasp on the world and our sketch of our project.

实现明天的唯一限制将是我们今天的疑虑。

I hope that in this year to come, you make mistakes. Because if you are making mistakes, then you are making new things, trying new things, learning, living, pushing yourself, changing yourself, changing your world.