Like a treatise on light and colours by a blind man.

The comparison questions an explanation because its author appears to lack firsthand experience of the subject. It suggests that the account may be unpersuasive despite its serious presentation.

It is a criticism of someone's presumed authority, not proof that their claims are wrong. The comparison rests on an assumption about what a person can know without direct sight.

Use this pointed comparison when challenging an account that seems detached from direct experience. It can sound dismissive, especially when experience is being treated as the only valid basis for knowledge.