As a side-line on this, there have been some very interesting programmes on the telly here just recently on the history of pornography. Pre-Victoria things were, of course, much freer and during the eighteenth century there was a particular 'flowering' of pornographic pamphlets. Pre-photography, of course, but very explicit cartoons, (specially on a largeish colour telly )
It's not at all certain their publication would be allowed today. At the time they were also seen as transgressive, but interestingly not because of the sexual content, but because of their ulterior purpose - which was in fact not sexual at all, but social unrest - the drawings were all of the nobility and upper classes and their purpose was to demean them and poke fun at them (preparing the way, eventually for bloody, or non-bloody revolution in Europe). Quite interesting that at this particular part of pornography's history there is a 'given' sense that graphic portrayal of - in this case - the sexual act or naughty bits in anticipation of same - is undeniably associated with the demeaning of those portrayed, and the amusement of those looking at them.
There's a classic story of Pepys pleasuring himself over one of them, and then immediately burning it as sinful/subversive. All recorded in his diaries