Explain why delusional perception is traditionally classified as a primary, 'un-understandable' delusion rather than a secondary one.

A secondary delusion can usually be traced back to something that makes emotional or psychological sense from the outside — profound guilt producing a delusion of having sinned, or fear producing a persecutory belief. Delusional perception attaches a false, private meaning to an entirely neutral, accurately perceived event, with no such traceable emotional or logical bridge between the perception and the belief it produces. That absence of any understandable connecting thread is exactly what makes it 'un-understandable' to an outside observer, and why it is treated as a primary rather than a secondary delusional phenomenon.