 Broadly speaking, Benjamin’s theory of Ideas transposes the philosophical problem of metaphysical realism into the context of aesthetics. That is, it asks about the reality of aesthetic genres such as ‘tragedy’ or of artistic epochs such as the ‘Renaissance’ that classify a group of particular works according to a set of common characteristics. The Prologue criticises existing traditions of aesthetic nominalism for their inadequate resolution of the problem. The uncritical use of inductive methods demonstrated by literary historians rejects the hypostatization of terms such as “Renaissance” on the grounds that it promotes a false identity between similar empirical features, which obscures their diversity. This aversion to any realism of constitutive Ideas is grounded on the positivist criterion of factual verification. A term like the “Renaissance” is consequently utilised by them only on the proviso that it is understood as merely an abstract general concept. This quickly leads to scepticism, however, since its still fails to address the problematic criteria by which this general concept is initially picked out and abstracted from the multiplicity of particulars or on what grounds these particulars are grouped together. Consequently, it fails to appreciate the necessity of the Platonic postulation of Ideas for the representation of essences: whilst concepts seek to make the similar identical, Ideas are necessary to effect a dialectical synthesis between phenomenal extremes (OGT, 18–19). In contrast, philosophers of art possess a concern with the essential that ends up renouncing any notion of generic forms, on the grounds that the singular originality of every single work entails the only possible essential genre must be the universal and individual one of art itself. The error—as Benjamin had previously charged the Early German Romantics, discussed above—is to dissolve real and important aesthetic structures or forms into an undifferentiated unity (of art), which denies their irreducible multiplicity (OGT, 21–23). 