The essential element in any classical composition is order. Although, all composition is order in one form or another, in classical composition order is associated with the idea of repose and possibly can exist for itself alone as an exercise, a stylistic gesture within confines rather than an imaginative projection into the realm of infinity.
A classic case of order, perfect order would be Vermeer’s The Artist In His Studio, where the space is tightly limited and defined, and within that room the various objects are so disposed that removing or altering any one of them would create a disconnect, a rupture, with the compositional sense of perfect order created by Vermeer.
In Poussin’s The Funeral of Phocion there is a similar attachment to perfect order within a bounded space. Here the sky is conceived as a backdrop terminating a stage set rather than a continuation of spece in nature. We are however, free to wander at will within this picture within the space abundant around the forms. More specifically, we are led to wander, directed as it is with no emergency exit for escape, but the objects are so harmoniously ordered that we do not feel imprisoned.
Poussin uses a number of devices that do not detract from spontaneous enjoyment, rooted as they are, in the artist’s feeling for what is right. A basic here is the repetition of the picture plane: the picture plane is repeated again and again as the objects recede towards the final backdrop which is the sky. A second series of planes at an angle to the picture plane is also suggested by the side plane of the wall forcing us to enter the picture from the lower left corner and moving across it, but we are impeded from moving out by the tall tree at the right and by this pane of the wall, which is turned to deflect the “current” of uor movement back into the picture. Like sheep being herded, even though this plane is in fact a distortion of true perspective.