What is the reason that solids do not spontaneously disintegrate into molecules of which they are composed?

Solids do not spontaneously disintegrate into molecules for the reason that the bond between the molecules of which they are composed is very strong. The molecules of a solid form a so-called crystal lattice, which helps to maintain the shape and volume of the solid. Therefore, without external influence, a solid will not disintegrate into molecules. For example, a piece of metal will not turn into liquid metal until it is subjected to a melting point.