"the clean bright orthogonal Mondrians"

Composition with Yellow, Blue and Red by Piet Mondrian
Public DomainComposition with Yellow, Blue and Red by Piet Mondrian
 Piet Mondrian (1872-1944) was a Dutch painter famous for his contributions to De Stilj (The Style), a Modernist movement in art. 'Orthogonal' in this context refers to the perpendicular lines which characterise Mondrian's work.