Do you have a particular work in mind? Generally speaking, we only tend to date the 'invention' of the earliest forms of pornography (obscenity) as a separate category about the time of the Renaissance in the fourteenth and fifteenth centuries. The creation of pornography as we know it dates to around 1850 in Western Europe.

Prior to the Renaissance, I doubt many authors would have seen erotic texts as 'pornographic' in the way that more modern people would have--the erotic and erotic language was a method of discourse (that is, sex was used as a metaphor) to critique religious and political figures.