text: The 19th century saw the classical age as being the precursor of academicism, including such movements as uniformitarianism in the sciences, and the creation of rigorous categories in artistic fields. Various movements of the Romantic period saw themselves as classical revolts against a prevailing trend of emotionalism and irregularity, for example the Pre-Raphaelites. By this point, classicism was old enough that previous classical movements received revivals; for example, the Renaissance was seen as a means to combine the organic medieval with the orderly classical. The 19th century continued or extended many classical programs in the sciences, most notably the Newtonian program to account for the movement of energy between bodies by means of exchange of mechanical and thermal energy.
  The 20th century saw a number of changes in the arts and sciences. Classicism was used both by those who rejected, or saw as temporary, transfigurations in the political, scientific, and social world and by those who embraced the changes as a means to overthrow the perceived weight of the 19th century. Thus, both pre-20th century disciplines were labelled "classical" and modern movements in art which saw themselves as aligned with light, space, sparseness of texture, and formal coherence.
  In the present day philosophy classicism is used as a term particularly in relation to Apollonian over Dionysian impulses in society and art; that is a preference for rationality, or at least rationally guided catharsis, over emotionalism.
  In the theatre
  Classicism in the theatre was developed by 17th century French playwrights from what they judged to be the rules of Greek classical theatre, including the "Classical unities" of time, place and action, found in the Poetics of Aristotle.
  Unity of time referred to the need for the entire action of the play to take place in a fictional 24-hour period
  Unity of place meant that the action should unfold in a single location