Why do liquids pour?

Liquids pour because they have a low viscosity.
A liquid will pour from a glass, because the bonds between the molecules are more flexible than in a solid. As you pour water from a glass, you can see how water bends toward the sink as it falls. The bonds between the water molecules are flexible enough to allow the water to bend, but strong enough to prevent it from falling apart. When you through a piece of wood into the air, the piece of wood doesn't bend as easily as water. This is because the bonds between the molecules are in wood are less flexible than in water. I hope this helps you to understand this process.