Classicism is art that is associated with antiquity, mainly Roman and Greek art and culture, and it includes such characteristics as symmetry, decorum, pellucidity, harmony and idealism. Classicism often arises out of a more primitive art form, and likewise gives rise to a more ornate, complex style.
Though classicism is strongly associated with the artistic ideals of the Roman and Greek cultures, there have been classical revivals in the various arts since antiquity. These later revivals are often labeled neoclassicism, though the characteristics of those periods are often identical or very similar to that of the original classical ideals.
Classicism is often a reaction to a less formal style during a prior artistic period that might be considered primitive to a classical revivalist. Classical art is more rigid than many other types of "period" art. For example, straight lines are more abundant than curves; compositions seem finished rather than flowing off the canvas; and the universal is preferred over the specific. The rigidity and clean lines of classicism have often engendered an artistic period of excess, which to a classicist would seem dissonant and unnecessarily ornate. An example of this is baroque art and music.
Many art historians and critics view the production of art as cyclical, with the classical phase as the pinnacle of achievement during each cycle. Because the original classical period of art is so highly regarded, the word "classic" implies perfection, or as close to perfection as is possible. Though each revival of the classical art forms share many general qualities, each neoclassical period reinterprets classical characteristics to harmonize with its particular era.