Molecules never sit still

In a gas, molecules fly in straight lines until they hit something. In a liquid they jostle in a crowd. Either way they are moving. Absolute zero is the idea of that motion stopping. Nothing you can hold in your hand is there.

Temperature is not a stuff poured in. It is the average kinetic energy of the molecules. Raise it and the same particles move faster. The element does not change. Only the motion does.

Vale's point: before you talk about Brownian motion or viscosity, see the crowd itself. The grain you watch later is pushed by this crowd.