It is also easier to ignite a fuel if it has a lot of surface area. A pile of wooden sticks is easier to ignite than a wooden log. The sticks have many, many times more surface area than the log. A fire is the burning of vaporised fuel, which when burnt produces heat, which in turn converts more fuel into vapour, thus continuing the burning cycle. Remember, if there is no ignition there is no fire.
Prevention is better than cure.
For advice on preventing fires around the home click here. The rate of fire growth depends on the fuel that is burning, and how much air can get to the fire. Fires in liquids and gases can grow very fast indeed. But some solid materials also burn very easily. Thin materials like curtains burn faster than thick materials.